metoprolol/hydrochlorothiazide (Rx)

Hypertension

Not indicated for initial therapy; if fixed combination represents dose titrated to patient’s needs, therapy with combination may be more convenient than with separate components

Lopressor HCT: metoprolol tartrate 50-100 mg and hydrochlorothiazide 25-50 mg PO daily in single or divided doses

Dutoprol: metoprolol succinate 25-100mg and hydrochlorothiazide 12.5 mg PO qDay as a single dose

When necessary, another antihypertensive agent may be added, beginning with 50% of usual recommended starting dose to avoid excessive fall in blood pressure

To minimize dose-independent side effects, begin combination therapy only after patient fails to achieve desired effect with monotherapy

Renal Impairment

Use caution in dosing/titrating patients with renal dysfunction

Cumulative effects of thiazides may develop with impaired renal function

Hepatic Impairment

No studies performed with metoprolol in patients with hepatic impairment

Because metoprolol succinate is metabolized by the liver, metoprolol blood levels are likely to increase substantially with poor hepatic function

Initiate therapy at doses lower than those recommended for a given indication, and increase doses gradually in patients with impaired hepatic function

Other Information

Combination may be substituted for titrated individual components

Withdraw gradually over a period of about 2 weeks

Geriatric: Start at low end of dosing range and titrate slowly

<18 years: Safety/efficacy not established

Hypertension

Not indicated for initial therapy; if fixed combination represents dose titrated to patient’s needs, therapy with combination may be more convenient than with separate components

Lopressor HCT: metoprolol tartrate 50-100 mg and hydrochlorothiazide 25-50 mg PO daily in single or divided doses

Dutoprol: metoprolol succinate 25-100mg amd hydrochlorothiazide 12.5 mg PO qDay as a single dose

When necessary, another antihypertensive agent may be added, beginning with 50% of usual recommended starting dose to avoid excessive fall in blood pressure

To minimize dose-independent side effects, begin combination therapy only after patient fails to achieve desired effect with monotherapy

Contraindicated (0)

Serious - Use Alternative (45)

• acebutolol

  acebutolol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• aminolevulinic acid oral

  aminolevulinic acid oral, hydrochlorothiazide. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid administering other phototoxic drugs with aminolevulinic acid oral for 24 hr during perioperative period.

• aminolevulinic acid topical

  hydrochlorothiazide increases toxicity of aminolevulinic acid topical by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration of photosensitizing drugs may enhance the phototoxic reaction to photodynamic therapy with aminolevulinic acid.

• artemether/lumefantrine

  artemether/lumefantrine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• atenolol

  atenolol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• betaxolol

  betaxolol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• bisoprolol

  bisoprolol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• carbamazepine

  carbamazepine, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased risk of systemic hyponatremia.

• carvedilol

  carvedilol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• celiprolol

  celiprolol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• chlorpromazine

  metoprolol, chlorpromazine. Either increases levels of the other by decreasing metabolism. Contraindicated. Not all beta blockers share this interaction (e.g., atenolol, nadolol, sotalol do not interact).

• clonidine

  clonidine, metoprolol. Either increases toxicity of the other by unspecified interaction mechanism. Avoid or Use Alternate Drug. Can increase risk of bradycardia.

• cyclophosphamide

  hydrochlorothiazide increases toxicity of cyclophosphamide by decreasing renal clearance. Avoid or Use Alternate Drug. Increased myelosuppressive effects.

• cyclosporine

  cyclosporine, hydrochlorothiazide. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased risk of systemic hyponatremia.

• dacomitinib

  dacomitinib will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid use with CYP2D6 substrates where minimal increases in concentration of the CYP2D6 substrate may lead to serious or life-threatening toxicities.

• digoxin

  digoxin increases toxicity of metoprolol by unspecified interaction mechanism. Avoid or Use Alternate Drug. Can increase risk of bradycardia.

• diltiazem

  diltiazem, metoprolol. Either increases toxicity of the other by unspecified interaction mechanism. Avoid or Use Alternate Drug. Can increase risk of bradycardia.

• dofetilide

  hydrochlorothiazide increases levels of dofetilide by decreasing renal clearance. Contraindicated. Risk of prolonged QTc interval.

• elvitegravir/cobicistat/emtricitabine/tenofovir DF

  elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Cobicistat is a CYP2D6 inhibitor; caution with CYP2D6 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.

• esmolol

  esmolol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• fexinidazole

  fexinidazole, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration of fexinidazole with drugs known to induce bradycardia. .

• fluoxetine

  fluoxetine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• givosiran

  givosiran will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP2D6 substrates with givosiran. If unavoidable, decrease the CYP2D6 substrate dosage in accordance with approved product labeling.

• isocarboxazid

  isocarboxazid, hydrochlorothiazide. Other (see comment). Contraindicated. Comment: Additive hypotensive effects may be seen when MAOI's are combined with antihypertensives.

• labetalol

  labetalol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• lofexidine

  lofexidine, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration with other drugs that decrease pulse or blood pressure to mitigate risk of excessive bradycardia and hypotension.
  
  lofexidine, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration with other drugs that decrease pulse or blood pressure to mitigate risk of excessive bradycardia and hypotension.

• lumefantrine

  lumefantrine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• methyl aminolevulinate

  hydrochlorothiazide, methyl aminolevulinate. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Each drug may increase the photosensitizing effect of the other.

• mavacamten

  metoprolol, mavacamten. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Expect additive negative inotropic effects of mavacamten and other drugs that reduce cardiac contractility.

• nadolol

  metoprolol and nadolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• nebivolol

  metoprolol and nebivolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• paroxetine

  paroxetine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• penbutolol

  metoprolol and penbutolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• pindolol

  metoprolol and pindolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• propranolol

  metoprolol and propranolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• quinidine

  quinidine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. If concurrent therapy required, monitor cardiac function carefully (blood pressure, heart rate). A dosage adjustment may be required for both drugs.

• rivastigmine

  metoprolol increases toxicity of rivastigmine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Additive bradycardia effect may result in syncope.

• sotalol

  metoprolol and sotalol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• squill

  hydrochlorothiazide increases toxicity of squill by Other (see comment). Avoid or Use Alternate Drug. Comment: Potassium depletion may enhance toxicity of squill.

• thioridazine

  metoprolol, thioridazine. Either increases levels of the other by decreasing metabolism. Contraindicated. Not all beta blockers share this interaction (e.g., atenolol, nadolol, sotalol do not interact).

• thiothixene

  metoprolol, thiothixene. Either increases levels of the other by decreasing metabolism. Contraindicated. Not all beta blockers share this interaction (e.g., atenolol, nadolol, sotalol do not interact).

• timolol

  metoprolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• tretinoin

  hydrochlorothiazide, tretinoin. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.

• tretinoin topical

  hydrochlorothiazide, tretinoin topical. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.

• verapamil

  verapamil, metoprolol. Either increases toxicity of the other by unspecified interaction mechanism. Avoid or Use Alternate Drug. Can increase risk of bradycardia.

Monitor Closely (279)

• abiraterone

  abiraterone increases levels of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Avoid coadministration of abiraterone with substrates of CYP2D6. If alternative therapy cannot be used, exercise caution and consider a dose reduction of the CYP2D6 substrate.

• acebutolol

  acebutolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  acebutolol and metoprolol both increase serum potassium. Use Caution/Monitor.

• aceclofenac

  aceclofenac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  aceclofenac decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and aceclofenac both increase serum potassium. Use Caution/Monitor.

• acemetacin

  metoprolol and acemetacin both increase serum potassium. Use Caution/Monitor.
  
  acemetacin decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  acemetacin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• albiglutide

  hydrochlorothiazide decreases effects of albiglutide by pharmacodynamic antagonism. Use Caution/Monitor. Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Monitor glycemic control especially when initiating, discontinuing, or increasing thiazide diuretic dose.

• albuterol

  metoprolol increases and albuterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol decreases effects of albuterol by pharmacodynamic antagonism. Use Caution/Monitor.

• albuterol

  albuterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• aldesleukin

  aldesleukin increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
  
  aldesleukin increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• alfuzosin

  alfuzosin and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• amifostine

  amifostine, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration with blood pressure lowering agents may increase the risk and severity of hypotension associated with amifostine. When amifostine is used at chemotherapeutic doses, withhold blood pressure lowering medications for 24 hr prior to amifostine; if blood pressure lowering medication cannot be withheld, do not administer amifostine.

• aluminum hydroxide

  aluminum hydroxide decreases levels of metoprolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

• amifostine

  amifostine, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration with blood pressure lowering agents may increase the risk and severity of hypotension associated with amifostine. When amifostine is used at chemotherapeutic doses, withhold blood pressure lowering medications for 24 hr prior to amifostine; if blood pressure lowering medication cannot be withheld, do not administer amifostine.

• amiloride

  metoprolol and amiloride both increase serum potassium. Modify Therapy/Monitor Closely.
  
  amiloride increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.

• amiodarone

  amiodarone will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Monitor cardiac function carefully and observe for signs of bradycardia or heart block when amiodarone and a beta adrenergic blocker are coadministered. Amiodarone should be used with caution in patients receiving a beta adrenergic blocker, particularly if there is suspicion of underlying dysfunction of the sinus node, such as bradycardia or sick sinus syndrome, or if there is partial AV block.
  
  amiodarone, metoprolol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of cardiotoxicity with bradycardia.
  
  amiodarone will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• amobarbital

  amobarbital decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of amobarbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• amoxicillin

  amoxicillin, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• arformoterol

  metoprolol decreases effects of arformoterol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  arformoterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and arformoterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• asenapine

  asenapine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  asenapine and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• aspirin

  aspirin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• aspirin

  metoprolol and aspirin both increase serum potassium. Use Caution/Monitor.
  
  aspirin decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• aspirin rectal

  aspirin rectal increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor. .
  
  aspirin rectal decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and aspirin rectal both increase serum potassium. Use Caution/Monitor.

• aspirin/citric acid/sodium bicarbonate

  metoprolol and aspirin/citric acid/sodium bicarbonate both increase serum potassium. Use Caution/Monitor.
  
  aspirin/citric acid/sodium bicarbonate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  aspirin/citric acid/sodium bicarbonate decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• atazanavir

  atazanavir increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of hypotension, bradycardia, AV block, and prolonged PR interval. Consider lowering beta blocker dose.

• atenolol

  atenolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• atenolol

  atenolol and metoprolol both increase serum potassium. Use Caution/Monitor.

• avanafil

  avanafil increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
  
  avanafil increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• beclomethasone, inhaled

  beclomethasone, inhaled increases toxicity of hydrochlorothiazide by increasing elimination. Use Caution/Monitor. May increase the hypokalemic effects of thiazide diuretics.

• bendroflumethiazide

  metoprolol increases and bendroflumethiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• benazepril

  benazepril increases toxicity of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Enhanced hypotensive effects; increased risk of nephrotoxicity.

• bendroflumethiazide

  bendroflumethiazide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• betaxolol

  betaxolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  betaxolol and metoprolol both increase serum potassium. Use Caution/Monitor.

• bismuth subsalicylate

  bismuth subsalicylate, metoprolol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Blockage of renal prostaglandin synthesis; may cause severe hypertension.

• bisoprolol

  bisoprolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• bisoprolol

  bisoprolol and metoprolol both increase serum potassium. Use Caution/Monitor.

• bretylium

  metoprolol, bretylium. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Each drug may cause hypotension.
  
  hydrochlorothiazide, bretylium. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Each drug may cause hypotension.

• bumetanide

  metoprolol increases and bumetanide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  bumetanide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• buprenorphine, long-acting injection

  buprenorphine, long-acting injection decreases effects of hydrochlorothiazide by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Opioids can reduce diuretic efficacy by inducing antidiuretic hormone release.

• bupropion

  bupropion will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• butabarbital

  butabarbital decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of butabarbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• butalbital

  butalbital decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of butalbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• calcifediol

  hydrochlorothiazide increases toxicity of calcifediol by Other (see comment). Use Caution/Monitor. Comment: Thiazide diuretics may increase serum calcium by decreasing urinary calcium excretion.

• calcium acetate

  calcium acetate decreases effects of metoprolol by unspecified interaction mechanism. Use Caution/Monitor.

• calcium carbonate

  calcium carbonate decreases effects of metoprolol by unspecified interaction mechanism. Use Caution/Monitor.
  
  calcium carbonate decreases levels of metoprolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

• calcium chloride

  calcium chloride decreases effects of metoprolol by unspecified interaction mechanism. Use Caution/Monitor.

• calcium citrate

  calcium citrate decreases effects of metoprolol by unspecified interaction mechanism. Use Caution/Monitor.

• calcium gluconate

  calcium gluconate decreases effects of metoprolol by unspecified interaction mechanism. Use Caution/Monitor.

• candesartan

  candesartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  candesartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  metoprolol, candesartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• captopril

  captopril, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Both drugs lower blood pressure. Increased risk of nephrotoxicity. Monitor blood pressure and renal function.

• carbenoxolone

  metoprolol increases and carbenoxolone decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• carbenoxolone

  hydrochlorothiazide and carbenoxolone both decrease serum potassium. Use Caution/Monitor.

• carbidopa

  carbidopa increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Therapy with carbidopa, given with or without levodopa or carbidopa-levodopa combination products, is started, dosage adjustment of the antihypertensive drug may be required.
  
  carbidopa increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Therapy with carbidopa, given with or without levodopa or carbidopa-levodopa combination products, is started, dosage adjustment of the antihypertensive drug may be required.

• carvedilol

  carvedilol and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  carvedilol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• cefprozil

  hydrochlorothiazide will increase the level or effect of cefprozil by acidic (anionic) drug competition for renal tubular clearance. Use Caution/Monitor.

• celecoxib

  celecoxib will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  metoprolol and celecoxib both increase serum potassium. Use Caution/Monitor.
  
  celecoxib decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• celecoxib

  celecoxib increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• celiprolol

  celiprolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  celiprolol and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  hydrochlorothiazide decreases levels of celiprolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.

• chloroquine

  chloroquine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• chlorothiazide

  chlorothiazide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• chlorothiazide

  metoprolol increases and chlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• chlorthalidone

  metoprolol increases and chlorthalidone decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  chlorthalidone and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• cholestyramine

  cholestyramine decreases levels of hydrochlorothiazide by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.

• choline magnesium trisalicylate

  metoprolol and choline magnesium trisalicylate both increase serum potassium. Use Caution/Monitor.
  
  choline magnesium trisalicylate decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• cimetidine

  cimetidine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• citalopram

  citalopram increases levels of metoprolol by decreasing metabolism. Use Caution/Monitor. Increased metoprolol plasma levels have been associated with decreased cardioselectivity.
  
  hydrochlorothiazide, citalopram. pharmacodynamic synergism. Use Caution/Monitor. Possible additive hyponatremia.

• clevidipine

  metoprolol and clevidipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• cornsilk

  cornsilk increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of hypokalemia (theoretical interaction).

• clonidine

  metoprolol, clonidine. Mechanism: pharmacodynamic synergism. Modify Therapy/Monitor Closely. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
  
  clonidine, metoprolol. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive sympatholytic action may worsen sinus node dysfunction and atrioventricular (AV) block.

• cobicistat

  cobicistat will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• corticotropin

  corticotropin increases toxicity of hydrochlorothiazide by increasing renal clearance. Use Caution/Monitor. May enhance hypokalemic effect of thiazide diuretics.

• cyclopenthiazide

  metoprolol increases and cyclopenthiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  cyclopenthiazide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• cyclosporine

  cyclosporine increases toxicity of hydrochlorothiazide by unspecified interaction mechanism. Use Caution/Monitor. Coadministration of hydrochlorothiazide with cyclosporine may increase the risk of hypermagnesemia, hyperuricemia, and possible nephrotoxicity.

• darifenacin

  darifenacin will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• darunavir

  darunavir will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• dasiglucagon

  metoprolol decreases effects of dasiglucagon by unknown mechanism. Use Caution/Monitor. Dasiglucagon may stimulate catecholamine release; whereas beta blockers may inhibit catecholamines released in response to dasiglucagon. Coadministration may also transiently increase pulse and BP.

• deflazacort

  hydrochlorothiazide and deflazacort both decrease serum potassium. Use Caution/Monitor.

• desflurane

  desflurane, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• desvenlafaxine

  desvenlafaxine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Desvenlafaxine inhibits CYP2D6; with higher desvenlafaxine doses (ie, 400 mg) decrease the CYP2D6 substrate dose by up to 50%; no dosage adjustment needed with desvenlafaxine doses <100 mg

• diazoxide

  hydrochlorothiazide increases toxicity of diazoxide by unspecified interaction mechanism. Use Caution/Monitor. May enhance hyperglycemic effects of diazoxide.

• dichlorphenamide

  dichlorphenamide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• diclofenac

  diclofenac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and diclofenac both increase serum potassium. Use Caution/Monitor.
  
  diclofenac decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• dicloxacillin

  dicloxacillin, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• diflunisal

  metoprolol and diflunisal both increase serum potassium. Use Caution/Monitor.
  
  diflunisal decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• diflunisal

  diflunisal increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• digoxin

  hydrochlorothiazide increases effects of digoxin by pharmacodynamic synergism. Use Caution/Monitor. Hypokalemia increases digoxin effects.
  
  digoxin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and digoxin both increase serum potassium. Use Caution/Monitor.
  
  digoxin will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
  
  metoprolol increases effects of digoxin by pharmacodynamic synergism. Use Caution/Monitor. Enhanced bradycardia.

• diltiazem

  metoprolol and diltiazem both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• dobutamine

  dobutamine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• diphenhydramine

  diphenhydramine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• dobutamine

  metoprolol increases and dobutamine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol decreases effects of dobutamine by pharmacodynamic antagonism. Use Caution/Monitor.

• dofetilide

  dofetilide will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• dopexamine

  dopexamine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and dopexamine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol decreases effects of dopexamine by pharmacodynamic antagonism. Use Caution/Monitor.

• doxazosin

  doxazosin and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• drospirenone

  drospirenone increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.

• dronedarone

  dronedarone will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• drospirenone

  metoprolol and drospirenone both increase serum potassium. Modify Therapy/Monitor Closely.

• duloxetine

  duloxetine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• eliglustat

  eliglustat increases levels of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the concomitant drug and titrate to clinical effect.

• empagliflozin

  empagliflozin, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration of empagliflozin with diuretics results in increased urine volume and frequency of voids, which might enhance the potential for volume depletion.

• ephedrine

  metoprolol increases and ephedrine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  ephedrine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol decreases effects of ephedrine by pharmacodynamic antagonism. Use Caution/Monitor.

• epinephrine

  epinephrine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and epinephrine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol decreases effects of epinephrine by pharmacodynamic antagonism. Use Caution/Monitor.

• epinephrine racemic

  metoprolol decreases effects of epinephrine racemic by pharmacodynamic antagonism. Use Caution/Monitor.
  
  metoprolol increases and epinephrine racemic decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  epinephrine racemic and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• eprosartan

  eprosartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  eprosartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol, eprosartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• esmolol

  esmolol and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  esmolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• ethacrynic acid

  metoprolol increases and ethacrynic acid decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  ethacrynic acid and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• ether

  metoprolol, ether. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Both beta blockers and ether depress the myocardium; consider lowering beta blocker dose if ether used for anesthesia.

• etodolac

  etodolac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• etodolac

  metoprolol and etodolac both increase serum potassium. Use Caution/Monitor.
  
  etodolac decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• etomidate

  etomidate, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• exenatide injectable solution

  hydrochlorothiazide decreases effects of exenatide injectable solution by pharmacodynamic antagonism. Use Caution/Monitor. Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Monitor glycemic control especially when initiating, discontinuing, or increasing thiazide diuretic dose.

• exenatide injectable suspension

  hydrochlorothiazide decreases effects of exenatide injectable suspension by pharmacodynamic antagonism. Use Caution/Monitor. Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Monitor glycemic control especially when initiating, discontinuing, or increasing thiazide diuretic dose.

• fedratinib

  fedratinib will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.

• felodipine

  metoprolol and felodipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• fenbufen

  metoprolol and fenbufen both increase serum potassium. Use Caution/Monitor.

• fenoprofen

  fenoprofen decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  fenoprofen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and fenoprofen both increase serum potassium. Use Caution/Monitor.

• fentanyl

  fentanyl decreases effects of hydrochlorothiazide by Other (see comment). Modify Therapy/Monitor Closely. Comment: Fentanyl can reduce the efficacy of diuretics by inducing antidiuretic hormone release. Fentanyl may also lead to acute urinary retention by causing bladder sphincter spasm (particularly in men with enlarged prostates).

• fingolimod

  metoprolol increases effects of fingolimod by pharmacodynamic synergism. Use Caution/Monitor. Both medications decrease heart rate. Monitor patients on concomitant therapy, particularly in the first 6 hours after fingolimod is initiated or after a treatment interruption of at least two weeks, for bradycardia and atrioventricular block. To identify underlying risk factors of bradycardia and AV block, obtain a new or recent ECG in patients using beta-blockers prior to starting fingolimod.

• fentanyl intranasal

  fentanyl intranasal decreases effects of hydrochlorothiazide by Other (see comment). Modify Therapy/Monitor Closely. Comment: Fentanyl can reduce the efficacy of diuretics by inducing antidiuretic hormone release. Fentanyl may also lead to acute urinary retention by causing bladder sphincter spasm (particularly in men with enlarged prostates).

• fentanyl transdermal

  fentanyl transdermal decreases effects of hydrochlorothiazide by Other (see comment). Modify Therapy/Monitor Closely. Comment: Fentanyl can reduce the efficacy of diuretics by inducing antidiuretic hormone release. Fentanyl may also lead to acute urinary retention by causing bladder sphincter spasm (particularly in men with enlarged prostates).

• fentanyl transmucosal

  fentanyl transmucosal decreases effects of hydrochlorothiazide by Other (see comment). Modify Therapy/Monitor Closely. Comment: Fentanyl can reduce the efficacy of diuretics by inducing antidiuretic hormone release. Fentanyl may also lead to acute urinary retention by causing bladder sphincter spasm (particularly in men with enlarged prostates).

• flurbiprofen

  flurbiprofen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and flurbiprofen both increase serum potassium. Use Caution/Monitor.
  
  flurbiprofen decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• formoterol

  formoterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol decreases effects of formoterol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  metoprolol increases and formoterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• furosemide

  metoprolol increases and furosemide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  furosemide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• gentamicin

  metoprolol increases and gentamicin decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydrochlorothiazide and gentamicin both decrease serum potassium. Use Caution/Monitor.

• glucagon

  glucagon decreases toxicity of metoprolol by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Coadministration of glucagon with beta-blockers may have transiently increased pulse and blood pressure.

• ibuprofen

  ibuprofen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• glucagon intranasal

  glucagon intranasal decreases toxicity of metoprolol by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Coadministration of glucagon with beta-blockers may have transiently increased pulse and blood pressure.

• haloperidol

  haloperidol will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• hydralazine

  hydralazine increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• hydrochlorothiazide

  metoprolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydrochlorothiazide, metoprolol. Either increases toxicity of the other by Other (see comment). Modify Therapy/Monitor Closely. Comment: May cause idiosyncratic reaction, resulting in acute transient myopia and acute angle-closure glaucoma, which can lead to permanent vision loss.

• ibuprofen

  metoprolol and ibuprofen both increase serum potassium. Use Caution/Monitor.
  
  ibuprofen decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• ibuprofen IV

  ibuprofen IV decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and ibuprofen IV both increase serum potassium. Use Caution/Monitor.
  
  hydrochlorothiazide will increase the level or effect of ibuprofen IV by acidic (anionic) drug competition for renal tubular clearance. Use Caution/Monitor.
  
  ibuprofen IV increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor. NSAIDs may decrease the therapeutic effects of thiazide-like diuretics; may also enhance nephrotoxic effects.

• imatinib

  imatinib will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• indacaterol, inhaled

  hydrochlorothiazide, indacaterol, inhaled. serum potassium. Use Caution/Monitor. Combination may increase risk of hypokalemia.
  
  indacaterol, inhaled, hydrochlorothiazide. Other (see comment). Use Caution/Monitor. Comment: Caution is advised in the coadministration of indacaterol neohaler with non-potassium-sparing diuretics.

• indacaterol, inhaled

  indacaterol, inhaled, metoprolol. Other (see comment). Use Caution/Monitor. Comment: Beta-blockers and indacaterol may interfere with the effect of each other when administered concurrently. Beta-blockers may produce severe bronchospasm in COPD patients. Therefore, patients with COPD should not normally be treated with beta-blockers. However, under certain circumstances, e.g. as prophylaxis after myocardial infarction, there may be no acceptable alternatives to the use of beta-blockers in patients with COPD. In this setting, cardioselective beta-blockers could be considered, although they should be administered with caution.

• indapamide

  hydrochlorothiazide and indapamide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and indapamide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• indomethacin

  indomethacin decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and indomethacin both increase serum potassium. Use Caution/Monitor.
  
  indomethacin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• insulin degludec

  metoprolol, insulin degludec. Other (see comment). Modify Therapy/Monitor Closely. Comment: Beta-blockers may either increase or decrease the blood glucose lowering effect of insulin; beta-blockers can prolong hypoglycemia (interference with glycogenolysis) or cause hyperglycemia (insulin secretion inhibited).
  
  hydrochlorothiazide decreases effects of insulin degludec by Other (see comment). Use Caution/Monitor. Comment: Diuretics may cause hyperglycemia and glycosuria in patients with diabetes mellitus, possibly by diuretic-induced hpokalemia.

• insulin degludec/insulin aspart

  metoprolol, insulin degludec/insulin aspart. Other (see comment). Modify Therapy/Monitor Closely. Comment: Beta-blockers may either increase or decrease the blood glucose lowering effect of insulin; beta-blockers can prolong hypoglycemia (interference with glycogenolysis) or cause hyperglycemia (insulin secretion inhibited).
  
  hydrochlorothiazide decreases effects of insulin degludec/insulin aspart by Other (see comment). Use Caution/Monitor. Comment: Diuretics may cause hyperglycemia and glycosuria in patients with diabetes mellitus, possibly by diuretic-induced hpokalemia.

• insulin inhaled

  metoprolol, insulin inhaled. Other (see comment). Modify Therapy/Monitor Closely. Comment: Beta-blockers may either increase or decrease the blood glucose lowering effect of insulin; beta-blockers can prolong hypoglycemia (interference with glycogenolysis) or cause hyperglycemia (insulin secretion inhibited).
  
  hydrochlorothiazide decreases effects of insulin inhaled by Other (see comment). Use Caution/Monitor. Comment: Diuretics may cause hyperglycemia and glycosuria in patients with diabetes mellitus, possibly by diuretic-induced hpokalemia.

• irbesartan

  irbesartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  irbesartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol, irbesartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• isoproterenol

  metoprolol increases and isoproterenol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  isoproterenol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol decreases effects of isoproterenol by pharmacodynamic antagonism. Use Caution/Monitor.

• isradipine

  metoprolol and isradipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• juniper

  juniper, hydrochlorothiazide. Other (see comment). Use Caution/Monitor. Comment: Juniper may potentiate or interfere with diuretic therapy. Juniper has diuretic effects, but may cause kidney damage at large doses.

• ivabradine

  ivabradine, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Most patients receiving ivabradine will also be treated with a beta-blocker. The risk of bradycardia increases with coadministration of drugs that slow heart rate (eg, digoxin, amiodarone, beta-blockers). Monitor heart rate in patients taking ivabradine with other negative chronotropes.

• ketamine

  ketamine, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• ketoprofen

  ketoprofen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  ketoprofen decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and ketoprofen both increase serum potassium. Use Caution/Monitor.

• ketorolac

  metoprolol and ketorolac both increase serum potassium. Use Caution/Monitor.
  
  ketorolac decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  ketorolac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• ketorolac intranasal

  ketorolac intranasal decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  ketorolac intranasal increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor. .
  
  metoprolol and ketorolac intranasal both increase serum potassium. Use Caution/Monitor.

• labetalol

  labetalol and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  labetalol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• levalbuterol

  metoprolol decreases effects of levalbuterol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  metoprolol increases and levalbuterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  levalbuterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• levodopa

  levodopa increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Consider decreasing dosage of antihypertensive agent.
  
  levodopa increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Consider decreasing dosage of antihypertensive agent.

• lily of the valley

  hydrochlorothiazide increases toxicity of lily of the valley by Other (see comment). Use Caution/Monitor. Comment: Increased risk of cardiac toxicity due to K+ depletion.

• lorcaserin

  lorcaserin will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• liraglutide

  hydrochlorothiazide decreases effects of liraglutide by pharmacodynamic antagonism. Use Caution/Monitor. Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Monitor glycemic control especially when initiating, discontinuing, or increasing thiazide diuretic dose.

• lithium

  hydrochlorothiazide increases toxicity of lithium by decreasing elimination. Use Caution/Monitor.

• lornoxicam

  metoprolol and lornoxicam both increase serum potassium. Use Caution/Monitor.
  
  lornoxicam increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  lornoxicam decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• losartan

  losartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  losartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol, losartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• lurasidone

  lurasidone increases effects of metoprolol by Other (see comment). Use Caution/Monitor. Comment: Potential for increased risk of hypotension with concurrent use. Monitor blood pressure and adjust dose of antihypertensive agent as needed.
  
  lurasidone increases effects of hydrochlorothiazide by Other (see comment). Use Caution/Monitor. Comment: Potential for increased risk of hypotension with concurrent use. Monitor blood pressure and adjust dose of antihypertensive agent as needed.

• maitake

  maitake increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of hypokalemia (theoretical interaction).

• maraviroc

  maraviroc will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• marijuana

  marijuana will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• meclofenamate

  meclofenamate decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and meclofenamate both increase serum potassium. Use Caution/Monitor.
  
  meclofenamate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• mefenamic acid

  mefenamic acid increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and mefenamic acid both increase serum potassium. Use Caution/Monitor.
  
  mefenamic acid decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• mefloquine

  mefloquine increases levels of metoprolol by decreasing metabolism. Use Caution/Monitor. Risk of arrhythmia.

• meloxicam

  meloxicam increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• meloxicam

  metoprolol and meloxicam both increase serum potassium. Use Caution/Monitor.
  
  meloxicam decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• metaproterenol

  metoprolol increases and metaproterenol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metaproterenol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol decreases effects of metaproterenol by pharmacodynamic antagonism. Use Caution/Monitor.

• methoxsalen

  methoxsalen, hydrochlorothiazide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive photosensitizing effects.

• methyclothiazide

  metoprolol increases and methyclothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor. .

• methylphenidate transdermal

  methylphenidate transdermal decreases effects of hydrochlorothiazide by anti-hypertensive channel blocking. Use Caution/Monitor.

• metolazone

  hydrochlorothiazide and metolazone both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and metolazone decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• metoprolol

  metoprolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydrochlorothiazide, metoprolol. Either increases toxicity of the other by Other (see comment). Modify Therapy/Monitor Closely. Comment: May cause idiosyncratic reaction, resulting in acute transient myopia and acute angle-closure glaucoma, which can lead to permanent vision loss.

• mirabegron

  mirabegron will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• mometasone inhaled

  mometasone inhaled increases toxicity of hydrochlorothiazide by Other (see comment). Use Caution/Monitor. Comment: Corticosteroids may increase hypokalemic effect of loop diuretics.

• moxisylyte

  moxisylyte and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• mycophenolate

  hydrochlorothiazide will increase the level or effect of mycophenolate by acidic (anionic) drug competition for renal tubular clearance. Use Caution/Monitor.

• nabumetone

  nabumetone increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  nabumetone decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and nabumetone both increase serum potassium. Use Caution/Monitor.

• nadolol

  metoprolol and nadolol both increase serum potassium. Use Caution/Monitor.
  
  nadolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• nafcillin

  nafcillin, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• naproxen

  metoprolol and naproxen both increase serum potassium. Use Caution/Monitor.
  
  naproxen decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• naproxen

  naproxen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• nebivolol

  nebivolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and nebivolol both increase serum potassium. Use Caution/Monitor.

• nicardipine

  metoprolol and nicardipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• nitroglycerin rectal

  nitroglycerin rectal, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Observe for possible additive hypotensive effects during concomitant use. .

• nifedipine

  metoprolol and nifedipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• nilotinib

  nilotinib will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• nisoldipine

  metoprolol and nisoldipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• nitroglycerin rectal

  nitroglycerin rectal, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Beta-blockers blunt the reflex tachycardia produced by nitroglycerin without preventing its hypotensive effects. If beta-blockers are used with nitroglycerin in patients with angina pectoris, additional hypotensive effects may occur.

• norepinephrine

  metoprolol decreases effects of norepinephrine by pharmacodynamic antagonism. Use Caution/Monitor.
  
  norepinephrine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and norepinephrine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• oliceridine

  oliceridine decreases effects of hydrochlorothiazide by Other (see comment). Use Caution/Monitor. Comment: Opioids can reduce the efficacy of diuretics by inducing the release of antidiuretic hormone. Monitor for signs of diminished diuresis and/or effects on blood pressure and increase dosage of the diuretic as needed. .

• olmesartan

  olmesartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  metoprolol, olmesartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• olmesartan

  olmesartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• olodaterol inhaled

  hydrochlorothiazide and olodaterol inhaled both decrease serum potassium. Use Caution/Monitor.

• oxaprozin

  metoprolol and oxaprozin both increase serum potassium. Use Caution/Monitor.
  
  oxaprozin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  oxaprozin decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• oxymetazoline topical

  oxymetazoline topical increases and metoprolol decreases sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• parecoxib

  parecoxib increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• panobinostat

  panobinostat will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Panobinostat can increase the levels and effects of sensitive CYP2D6 substrates or those with a narrow therapeutic index CYP2D6.

• parecoxib

  parecoxib will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  metoprolol and parecoxib both increase serum potassium. Use Caution/Monitor.
  
  parecoxib decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• peginterferon alfa 2b

  peginterferon alfa 2b, metoprolol. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate.

• penbutolol

  penbutolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and penbutolol both increase serum potassium. Use Caution/Monitor.

• penicillin G aqueous

  penicillin G aqueous, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• pentobarbital

  pentobarbital decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of pentobarbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• perphenazine

  perphenazine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• phenobarbital

  phenobarbital decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of phenobarbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• phenoxybenzamine

  phenoxybenzamine and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• phentolamine

  phentolamine and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• pindolol

  pindolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and pindolol both increase serum potassium. Use Caution/Monitor.

• pirbuterol

  metoprolol decreases effects of pirbuterol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  pirbuterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and pirbuterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• piroxicam

  piroxicam increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and piroxicam both increase serum potassium. Use Caution/Monitor.
  
  piroxicam decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• pivmecillinam

  pivmecillinam, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• ponesimod

  ponesimod and metoprolol both increase pharmacodynamic synergism. Use Caution/Monitor. Beta-blockers may have additive effects on lowering HR. Consider resting HR before initiating ponesimod in patients on stable dose of beta-blocker. Refer to the ponesimod prescribing information for more dosing information.

• porfimer

  hydrochlorothiazide, porfimer. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Enhanced photosensitivity.

• potassium acid phosphate

  potassium acid phosphate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.
  
  metoprolol and potassium acid phosphate both increase serum potassium. Modify Therapy/Monitor Closely.

• potassium chloride

  metoprolol and potassium chloride both increase serum potassium. Modify Therapy/Monitor Closely.
  
  potassium chloride increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.

• potassium citrate

  metoprolol and potassium citrate both increase serum potassium. Modify Therapy/Monitor Closely.
  
  potassium citrate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.

• prazosin

  prazosin and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• probenecid

  hydrochlorothiazide will increase the level or effect of probenecid by acidic (anionic) drug competition for renal tubular clearance. Use Caution/Monitor.

• primidone

  primidone decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of primidone. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• procainamide

  hydrochlorothiazide will increase the level or effect of procainamide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• propafenone

  propafenone will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent therapy is required, monitor cardiac function carefully, particularly blood pressure. A dosage adjustment for the beta blocker may be required.

• propofol

  propofol, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• propranolol

  metoprolol and propranolol both increase serum potassium. Use Caution/Monitor.
  
  propranolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• quinacrine

  quinacrine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• quinidine

  quinidine will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• ranolazine

  ranolazine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• rifabutin

  rifabutin decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Enzyme induction effect may continue for up to 3-4 weeks.

• rifampin

  rifampin decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor.

• rifapentine

  rifapentine decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor.

• ritonavir

  ritonavir will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• rolapitant

  rolapitant will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Rolapitant may increase plasma concentrations of CYP2D6 substrates for at least 28 days following rolapitant administration.

• sacubitril/valsartan

  sacubitril/valsartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  sacubitril/valsartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  metoprolol, sacubitril/valsartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• salicylates (non-asa)

  salicylates (non-asa) decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and salicylates (non-asa) both increase serum potassium. Use Caution/Monitor.
  
  salicylates (non-asa) increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• salmeterol

  metoprolol decreases effects of salmeterol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  salmeterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and salmeterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• salsalate

  salsalate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  salsalate decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and salsalate both increase serum potassium. Use Caution/Monitor.

• saquinavir

  saquinavir, metoprolol. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Use alternatives if available. Increased risk of PR prolongation and cardiac arrhythmias.

• shark cartilage

  hydrochlorothiazide, shark cartilage. Other (see comment). Use Caution/Monitor. Comment: May lead to hypercalcemia (theoretical).

• secobarbital

  secobarbital decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of secobarbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• sertraline

  sertraline will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• sevoflurane

  sevoflurane, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• sildenafil

  metoprolol increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.

• silodosin

  silodosin and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• siponimod

  siponimod, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Caution when siponimod is initiated in patients receiving beta-blocker treatment because of additive effects on lowering heart rate. Temporary interruption of beta-blocker may be needed before initiating siponimod. Beta-blocker treatment can be initiated in patients receiving stable doses of siponimod.

• sodium bicarbonate

  sodium bicarbonate decreases levels of metoprolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

• sodium citrate/citric acid

  sodium citrate/citric acid decreases levels of metoprolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

• sodium sulfate/?magnesium sulfate/potassium chloride

  sodium sulfate/?magnesium sulfate/potassium chloride increases toxicity of hydrochlorothiazide by Other (see comment). Use Caution/Monitor. Comment: Coadministration with medications that cause fluid and electrolyte abnormalities may increase the risk of adverse events of seizure, arrhythmias, and renal impairment.

• sodium sulfate/potassium chloride/magnesium sulfate/polyethylene glycol

  hydrochlorothiazide and sodium sulfate/potassium chloride/magnesium sulfate/polyethylene glycol both decrease serum potassium. Modify Therapy/Monitor Closely.

• sodium sulfate/potassium sulfate/magnesium sulfate

  sodium sulfate/potassium sulfate/magnesium sulfate increases toxicity of hydrochlorothiazide by Other (see comment). Use Caution/Monitor. Comment: Coadministration with medications that cause fluid and electrolyte abnormalities may increase the risk of adverse events of seizure, arrhythmias, and renal impairment.

• sotalol

  metoprolol and sotalol both increase serum potassium. Use Caution/Monitor.
  
  sotalol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• spironolactone

  spironolactone increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.
  
  metoprolol and spironolactone both increase serum potassium. Modify Therapy/Monitor Closely.

• succinylcholine

  succinylcholine increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and succinylcholine both increase serum potassium. Use Caution/Monitor.

• sulfasalazine

  metoprolol and sulfasalazine both increase serum potassium. Use Caution/Monitor.
  
  sulfasalazine decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  sulfasalazine increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• sulindac

  metoprolol and sulindac both increase serum potassium. Use Caution/Monitor.
  
  sulindac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  sulindac decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• tadalafil

  tadalafil increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
  
  tadalafil increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• telmisartan

  telmisartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  telmisartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol, telmisartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• temocillin

  temocillin, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• terazosin

  terazosin and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• terbinafine

  terbinafine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.

• terbutaline

  metoprolol decreases effects of terbutaline by pharmacodynamic antagonism. Use Caution/Monitor.
  
  metoprolol increases and terbutaline decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol increases effects of terbutaline by pharmacodynamic synergism. Use Caution/Monitor.
  
  terbutaline and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• theophylline

  metoprolol, theophylline. Other (see comment). Use Caution/Monitor. Comment: Beta blockers (esp. non selective) antagonize theophylline effects, while at the same time increasing theophylline levels and toxicity (mechanism: decreased theophylline metabolism). Smoking increases risk of interaction.

• ticarcillin

  ticarcillin, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• thioridazine

  thioridazine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• timolol

  timolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and timolol both increase serum potassium. Use Caution/Monitor.

• tipranavir

  tipranavir will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• tolfenamic acid

  tolfenamic acid increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• tolfenamic acid

  metoprolol and tolfenamic acid both increase serum potassium. Use Caution/Monitor.
  
  tolfenamic acid decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• tolmetin

  tolmetin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and tolmetin both increase serum potassium. Use Caution/Monitor.
  
  tolmetin decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

• tolvaptan

  tolvaptan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and tolvaptan both increase serum potassium. Use Caution/Monitor.

• toremifene

  hydrochlorothiazide, toremifene. Other (see comment). Use Caution/Monitor. Comment: Thiazide diuretics decrease renal calcium excretion and may increase risk of hypercalcemia in patients taking toremifene.

• torsemide

  metoprolol increases and torsemide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• torsemide

  torsemide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• triamterene

  triamterene increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.
  
  metoprolol and triamterene both increase serum potassium. Modify Therapy/Monitor Closely.

• trientine

  hydrochlorothiazide decreases levels of trientine by increasing renal clearance. Use Caution/Monitor.

• valsartan

  valsartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  metoprolol, valsartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• umeclidinium bromide/vilanterol inhaled

  umeclidinium bromide/vilanterol inhaled and hydrochlorothiazide both decrease serum potassium. Modify Therapy/Monitor Closely. Electrocardiographic changes and/or hypokalemia associated with non?potassium-sparing diuretics may worsen with concomitant beta-agonists, particularly if recommended dose is exceeded

• valsartan

  valsartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• venlafaxine

  venlafaxine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• verapamil

  metoprolol and verapamil both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• vilanterol/fluticasone furoate inhaled

  vilanterol/fluticasone furoate inhaled and hydrochlorothiazide both decrease serum potassium. Modify Therapy/Monitor Closely. Beta-agonists may acutely worsen ECG changes and/or hypokalemia resulting from non-potassium-sparing diuretics

• vitamin D

  hydrochlorothiazide increases effects of vitamin D by Other (see comment). Use Caution/Monitor. Comment: Combination may increase hypercalcemic effect of vitamin D analogs. Use with caution.

• xipamide

  xipamide increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor.
  
  xipamide increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor.

Minor (175)

• acarbose

  hydrochlorothiazide decreases effects of acarbose by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• aceclofenac

  hydrochlorothiazide will increase the level or effect of aceclofenac by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• acemetacin

  hydrochlorothiazide will increase the level or effect of acemetacin by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• acyclovir

  hydrochlorothiazide will increase the level or effect of acyclovir by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• adenosine

  metoprolol, adenosine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Bradycardia.

• agrimony

  agrimony increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.
  
  agrimony increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• albuterol

  albuterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• antipyrine

  metoprolol increases levels of antipyrine by decreasing metabolism. Minor/Significance Unknown.

• aminohippurate sodium

  hydrochlorothiazide will increase the level or effect of aminohippurate sodium by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• ampicillin

  hydrochlorothiazide increases levels of ampicillin by decreasing renal clearance. Minor/Significance Unknown.

• arformoterol

  arformoterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• aspirin

  hydrochlorothiazide will increase the level or effect of aspirin by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• aspirin rectal

  hydrochlorothiazide will increase the level or effect of aspirin rectal by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• aspirin/citric acid/sodium bicarbonate

  hydrochlorothiazide will increase the level or effect of aspirin/citric acid/sodium bicarbonate by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• balsalazide

  hydrochlorothiazide will increase the level or effect of balsalazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• bendroflumethiazide

  bendroflumethiazide will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• birch

  birch increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.

• bitter melon

  bitter melon, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• brimonidine

  brimonidine increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.
  
  brimonidine increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• budesonide

  budesonide, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• cevimeline

  cevimeline increases effects of metoprolol by unspecified interaction mechanism. Minor/Significance Unknown.

• calcitriol topical

  calcitriol topical, hydrochlorothiazide. Either increases toxicity of the other by pharmacodynamic synergism. Minor/Significance Unknown. Potential additive hypercalcemia.

• calcium acetate

  hydrochlorothiazide increases levels of calcium acetate by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• calcium carbonate

  hydrochlorothiazide increases levels of calcium carbonate by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• calcium chloride

  hydrochlorothiazide increases levels of calcium chloride by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• calcium citrate

  hydrochlorothiazide increases levels of calcium citrate by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• calcium gluconate

  hydrochlorothiazide increases levels of calcium gluconate by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• carbenoxolone

  hydrochlorothiazide, carbenoxolone. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive hypokalemic effects.

• cefadroxil

  cefadroxil will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• cefamandole

  cefamandole will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• cefpirome

  cefpirome will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• cefprozil

  cefprozil will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• ceftibuten

  ceftibuten will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• celecoxib

  hydrochlorothiazide will increase the level or effect of celecoxib by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• cephalexin

  cephalexin will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• chlorothiazide

  chlorothiazide will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• chlorpropamide

  hydrochlorothiazide will increase the level or effect of chlorpropamide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.
  
  hydrochlorothiazide decreases effects of chlorpropamide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• chlorthalidone

  chlorthalidone will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• ciprofloxacin

  ciprofloxacin increases levels of metoprolol by decreasing metabolism. Minor/Significance Unknown. Ciprofloxacin may increase metoprolol plasma concentrations however mechanism is unknown. Further clinical evidence is needed but it may be appropriate to monitor patients during concomitant therapy with ciprofloxacin.

• cocaine topical

  metoprolol increases effects of cocaine topical by pharmacodynamic synergism. Minor/Significance Unknown. Risk of angina.

• colestipol

  colestipol decreases levels of hydrochlorothiazide by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

• cornsilk

  cornsilk increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• cortisone

  cortisone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• cosyntropin

  cosyntropin, hydrochlorothiazide. pharmacodynamic synergism. Minor/Significance Unknown. Possible enhanced electrolyte loss.

• cyclopenthiazide

  cyclopenthiazide will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• deflazacort

  deflazacort, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• dexamethasone

  dexamethasone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• diazepam

  metoprolol increases effects of diazepam by decreasing metabolism. Minor/Significance Unknown.

• diazoxide

  diazoxide, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperglycemia.

• diclofenac

  hydrochlorothiazide will increase the level or effect of diclofenac by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• diflunisal

  hydrochlorothiazide will increase the level or effect of diflunisal by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• dihydroergotamine

  dihydroergotamine, metoprolol. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive vasospasm.

• dihydroergotamine intranasal

  dihydroergotamine intranasal, metoprolol. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive vasospasm.

• dipyridamole

  dipyridamole, metoprolol. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of bradycardia.

• dobutamine

  dobutamine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• dopexamine

  dopexamine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• ephedrine

  ephedrine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• epinephrine

  epinephrine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• epinephrine racemic

  epinephrine racemic, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• epoprostenol

  epoprostenol increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown. Additive hypotensive effects.

• escitalopram

  escitalopram increases levels of metoprolol by decreasing metabolism. Minor/Significance Unknown.

• etodolac

  hydrochlorothiazide will increase the level or effect of etodolac by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• fenbufen

  hydrochlorothiazide will increase the level or effect of fenbufen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• fenoldopam

  fenoldopam increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown. Additive hypotensive effects.

• fenoprofen

  hydrochlorothiazide will increase the level or effect of fenoprofen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• fludrocortisone

  fludrocortisone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• flurbiprofen

  hydrochlorothiazide will increase the level or effect of flurbiprofen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• fo-ti

  fo-ti increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia (theoretical).

• folic acid

  hydrochlorothiazide decreases levels of folic acid by increasing renal clearance. Minor/Significance Unknown.

• formoterol

  formoterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• forskolin

  forskolin increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.
  
  forskolin increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.

• ganciclovir

  hydrochlorothiazide will increase the level or effect of ganciclovir by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• guanfacine

  metoprolol, guanfacine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.

• glimepiride

  hydrochlorothiazide decreases effects of glimepiride by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• glipizide

  hydrochlorothiazide decreases effects of glipizide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• glyburide

  hydrochlorothiazide decreases effects of glyburide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• goldenrod

  goldenrod increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.

• hydrocortisone

  hydrocortisone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• ibuprofen

  hydrochlorothiazide will increase the level or effect of ibuprofen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• imaging agents (gadolinium)

  metoprolol, imaging agents (gadolinium). Mechanism: unknown. Minor/Significance Unknown. Increased risk of anaphylaxis from contrast media.

• indapamide

  hydrochlorothiazide will increase the level or effect of indapamide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• indomethacin

  hydrochlorothiazide will increase the level or effect of indomethacin by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• insulin aspart

  hydrochlorothiazide decreases effects of insulin aspart by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• insulin detemir

  hydrochlorothiazide decreases effects of insulin detemir by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• insulin glargine

  hydrochlorothiazide decreases effects of insulin glargine by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• insulin glulisine

  hydrochlorothiazide decreases effects of insulin glulisine by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• insulin lispro

  hydrochlorothiazide decreases effects of insulin lispro by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• insulin NPH

  hydrochlorothiazide decreases effects of insulin NPH by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• insulin regular human

  hydrochlorothiazide decreases effects of insulin regular human by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• isoproterenol

  isoproterenol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• ketoprofen

  hydrochlorothiazide will increase the level or effect of ketoprofen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• ketorolac

  hydrochlorothiazide will increase the level or effect of ketorolac by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• ketorolac intranasal

  hydrochlorothiazide will increase the level or effect of ketorolac intranasal by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• L-methylfolate

  hydrochlorothiazide decreases levels of L-methylfolate by increasing renal clearance. Minor/Significance Unknown.

• levalbuterol

  levalbuterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• levobetaxolol

  levobetaxolol increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• lornoxicam

  hydrochlorothiazide will increase the level or effect of lornoxicam by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• magnesium chloride

  hydrochlorothiazide decreases levels of magnesium chloride by increasing renal clearance. Minor/Significance Unknown.

• magnesium citrate

  hydrochlorothiazide decreases levels of magnesium citrate by increasing renal clearance. Minor/Significance Unknown.

• magnesium hydroxide

  hydrochlorothiazide decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

• magnesium oxide

  hydrochlorothiazide decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

• magnesium sulfate

  hydrochlorothiazide decreases levels of magnesium sulfate by increasing renal clearance. Minor/Significance Unknown.

• maitake

  maitake increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• meclofenamate

  hydrochlorothiazide will increase the level or effect of meclofenamate by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• mefenamic acid

  hydrochlorothiazide will increase the level or effect of mefenamic acid by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• meloxicam

  hydrochlorothiazide will increase the level or effect of meloxicam by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• memantine

  hydrochlorothiazide will increase the level or effect of memantine by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• mesalamine

  hydrochlorothiazide will increase the level or effect of mesalamine by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• metaproterenol

  metaproterenol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• metformin

  hydrochlorothiazide will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
  
  hydrochlorothiazide decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• methotrexate

  hydrochlorothiazide increases toxicity of methotrexate by decreasing elimination. Minor/Significance Unknown. Increased myelosuppression.

• methylprednisolone

  methylprednisolone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• metipranolol ophthalmic

  metipranolol ophthalmic increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• metolazone

  hydrochlorothiazide will increase the level or effect of metolazone by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• midodrine

  hydrochlorothiazide will increase the level or effect of midodrine by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• miglitol

  hydrochlorothiazide decreases effects of miglitol by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• minoxidil

  hydrochlorothiazide increases effects of minoxidil by pharmacodynamic synergism. Minor/Significance Unknown.

• nabumetone

  hydrochlorothiazide will increase the level or effect of nabumetone by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• naproxen

  hydrochlorothiazide will increase the level or effect of naproxen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• nateglinide

  hydrochlorothiazide decreases effects of nateglinide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• neostigmine

  metoprolol, neostigmine. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive bradycardia.

• noni juice

  metoprolol and noni juice both increase serum potassium. Minor/Significance Unknown.
  
  noni juice increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Minor/Significance Unknown.

• norepinephrine

  norepinephrine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.
  
  hydrochlorothiazide decreases effects of norepinephrine by pharmacodynamic antagonism. Minor/Significance Unknown. May decrease responsiveness to norepinephrine but not enough to preclude effectiveness of the pressor agent therapeutic use.

• octacosanol

  octacosanol increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• octacosanol

  octacosanol increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.

• ofloxacin

  hydrochlorothiazide will increase the level or effect of ofloxacin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• oxaprozin

  hydrochlorothiazide will increase the level or effect of oxaprozin by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• oxazepam

  metoprolol increases effects of oxazepam by decreasing metabolism. Minor/Significance Unknown.

• parecoxib

  hydrochlorothiazide will increase the level or effect of parecoxib by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• patiromer

  patiromer, metoprolol. cation binding in GI tract. Minor/Significance Unknown. No observed clinically important interaction. No separation of dosing required.

• penicillin G aqueous

  hydrochlorothiazide increases levels of penicillin G aqueous by decreasing renal clearance. Minor/Significance Unknown.

• penicillin VK

  hydrochlorothiazide increases levels of penicillin VK by decreasing renal clearance. Minor/Significance Unknown.

• physostigmine

  metoprolol, physostigmine. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive bradycardia.

• pilocarpine

  pilocarpine increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• pioglitazone

  hydrochlorothiazide decreases effects of pioglitazone by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• piperacillin

  hydrochlorothiazide increases levels of piperacillin by decreasing renal clearance. Minor/Significance Unknown.

• pirbuterol

  pirbuterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• piroxicam

  hydrochlorothiazide will increase the level or effect of piroxicam by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• prednisolone

  prednisolone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• prednisone

  prednisone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• quinine

  hydrochlorothiazide will increase the level or effect of quinine by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• reishi

  reishi increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.
  
  reishi increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• repaglinide

  hydrochlorothiazide decreases effects of repaglinide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• shepherd's purse

  shepherd's purse, metoprolol. Other (see comment). Minor/Significance Unknown. Comment: Theoretically, shepherd's purse may interfere with BP control.

• rose hips

  rose hips will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• rosiglitazone

  hydrochlorothiazide decreases effects of rosiglitazone by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• salicylates (non-asa)

  hydrochlorothiazide will increase the level or effect of salicylates (non-asa) by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• salmeterol

  salmeterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• salsalate

  hydrochlorothiazide will increase the level or effect of salsalate by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• saxagliptin

  hydrochlorothiazide decreases effects of saxagliptin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• shepherd's purse

  shepherd's purse, hydrochlorothiazide. Other (see comment). Minor/Significance Unknown. Comment: Theoretically, shepherd's purse may interfere with BP control.

• sitagliptin

  hydrochlorothiazide decreases effects of sitagliptin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• sulfadiazine

  hydrochlorothiazide increases levels of sulfadiazine by unspecified interaction mechanism. Minor/Significance Unknown.

• sulfamethoxazole

  sulfamethoxazole will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
  
  hydrochlorothiazide increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
  
  hydrochlorothiazide, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.

• sulfasalazine

  hydrochlorothiazide will increase the level or effect of sulfasalazine by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• sulfisoxazole

  hydrochlorothiazide increases levels of sulfisoxazole by unspecified interaction mechanism. Minor/Significance Unknown.

• sulindac

  hydrochlorothiazide will increase the level or effect of sulindac by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• terbutaline

  terbutaline, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.
  
  hydrochlorothiazide, terbutaline. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive hypokalemic effects.

• tizanidine

  tizanidine increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypotension.
  
  tizanidine increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypotension.

• tolazamide

  hydrochlorothiazide decreases effects of tolazamide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• treprostinil

  treprostinil increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• tolbutamide

  hydrochlorothiazide decreases effects of tolbutamide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• tolfenamic acid

  hydrochlorothiazide will increase the level or effect of tolfenamic acid by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• tolmetin

  hydrochlorothiazide will increase the level or effect of tolmetin by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• treprostinil

  treprostinil increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.

• triamcinolone acetonide injectable suspension

  triamcinolone acetonide injectable suspension, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• triamterene

  hydrochlorothiazide will increase the level or effect of triamterene by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• trilostane

  trilostane, hydrochlorothiazide. Other (see comment). Minor/Significance Unknown. Comment: Trilostane reduces K+ loss while maintaining the natriuretic effect. Mechanism: inhibition of mineralocorticoid steroid synthesis.

• trimethoprim

  hydrochlorothiazide will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
  
  hydrochlorothiazide, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.

• valganciclovir

  hydrochlorothiazide will increase the level or effect of valganciclovir by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• verapamil

  hydrochlorothiazide will increase the level or effect of verapamil by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• verteporfin

  hydrochlorothiazide, verteporfin. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Increased phototoxicity.

• vildagliptin

  hydrochlorothiazide decreases effects of vildagliptin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• willow bark

  hydrochlorothiazide will increase the level or effect of willow bark by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• yohimbe

  metoprolol decreases toxicity of yohimbe by pharmacodynamic antagonism. Minor/Significance Unknown.

• abiraterone

  Monitor Closely (1)abiraterone increases levels of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Avoid coadministration of abiraterone with substrates of CYP2D6. If alternative therapy cannot be used, exercise caution and consider a dose reduction of the CYP2D6 substrate.

• acarbose

  Minor (1)hydrochlorothiazide decreases effects of acarbose by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• acebutolol

  Monitor Closely (2)acebutolol and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  acebutolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)acebutolol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• aceclofenac

  Monitor Closely (3)aceclofenac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  aceclofenac decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and aceclofenac both increase serum potassium. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of aceclofenac by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• acemetacin

  Monitor Closely (3)metoprolol and acemetacin both increase serum potassium. Use Caution/Monitor.
  
  acemetacin decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  acemetacin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of acemetacin by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• acyclovir

  Minor (1)hydrochlorothiazide will increase the level or effect of acyclovir by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• adenosine

  Minor (1)metoprolol, adenosine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Bradycardia.

• agrimony

  Minor (2)agrimony increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.
  
  agrimony increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• albiglutide

  Monitor Closely (1)hydrochlorothiazide decreases effects of albiglutide by pharmacodynamic antagonism. Use Caution/Monitor. Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Monitor glycemic control especially when initiating, discontinuing, or increasing thiazide diuretic dose.

• albuterol

  Monitor Closely (3)metoprolol decreases effects of albuterol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  metoprolol increases and albuterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  albuterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)albuterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• aldesleukin

  Monitor Closely (2)aldesleukin increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
  
  aldesleukin increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• alfuzosin

  Monitor Closely (1)alfuzosin and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• aluminum hydroxide

  Monitor Closely (1)aluminum hydroxide decreases levels of metoprolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

• amifostine

  Monitor Closely (2)amifostine, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration with blood pressure lowering agents may increase the risk and severity of hypotension associated with amifostine. When amifostine is used at chemotherapeutic doses, withhold blood pressure lowering medications for 24 hr prior to amifostine; if blood pressure lowering medication cannot be withheld, do not administer amifostine.
  
  amifostine, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration with blood pressure lowering agents may increase the risk and severity of hypotension associated with amifostine. When amifostine is used at chemotherapeutic doses, withhold blood pressure lowering medications for 24 hr prior to amifostine; if blood pressure lowering medication cannot be withheld, do not administer amifostine.

• amiloride

  Monitor Closely (2)metoprolol and amiloride both increase serum potassium. Modify Therapy/Monitor Closely.
  
  amiloride increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.

• aminohippurate sodium

  Minor (1)hydrochlorothiazide will increase the level or effect of aminohippurate sodium by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• aminolevulinic acid oral

  Serious - Use Alternative (1)aminolevulinic acid oral, hydrochlorothiazide. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid administering other phototoxic drugs with aminolevulinic acid oral for 24 hr during perioperative period.

• aminolevulinic acid topical

  Serious - Use Alternative (1)hydrochlorothiazide increases toxicity of aminolevulinic acid topical by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration of photosensitizing drugs may enhance the phototoxic reaction to photodynamic therapy with aminolevulinic acid.

• amiodarone

  Monitor Closely (3)amiodarone will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Monitor cardiac function carefully and observe for signs of bradycardia or heart block when amiodarone and a beta adrenergic blocker are coadministered. Amiodarone should be used with caution in patients receiving a beta adrenergic blocker, particularly if there is suspicion of underlying dysfunction of the sinus node, such as bradycardia or sick sinus syndrome, or if there is partial AV block.
  
  amiodarone, metoprolol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of cardiotoxicity with bradycardia.
  
  amiodarone will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• amobarbital

  Monitor Closely (1)amobarbital decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of amobarbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• amoxicillin

  Monitor Closely (1)amoxicillin, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• ampicillin

  Minor (1)hydrochlorothiazide increases levels of ampicillin by decreasing renal clearance. Minor/Significance Unknown.

• antipyrine

  Minor (1)metoprolol increases levels of antipyrine by decreasing metabolism. Minor/Significance Unknown.

• arformoterol

  Monitor Closely (3)metoprolol decreases effects of arformoterol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  arformoterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and arformoterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)arformoterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• artemether/lumefantrine

  Serious - Use Alternative (1)artemether/lumefantrine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• asenapine

  Monitor Closely (2)asenapine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  asenapine and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• aspirin

  Monitor Closely (3)metoprolol and aspirin both increase serum potassium. Use Caution/Monitor.
  
  aspirin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  aspirin decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.Minor (1)hydrochlorothiazide will increase the level or effect of aspirin by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• aspirin rectal

  Monitor Closely (3)aspirin rectal increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor. .
  
  aspirin rectal decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and aspirin rectal both increase serum potassium. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of aspirin rectal by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• aspirin/citric acid/sodium bicarbonate

  Monitor Closely (3)metoprolol and aspirin/citric acid/sodium bicarbonate both increase serum potassium. Use Caution/Monitor.
  
  aspirin/citric acid/sodium bicarbonate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  aspirin/citric acid/sodium bicarbonate decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.Minor (1)hydrochlorothiazide will increase the level or effect of aspirin/citric acid/sodium bicarbonate by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• atazanavir

  Monitor Closely (1)atazanavir increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of hypotension, bradycardia, AV block, and prolonged PR interval. Consider lowering beta blocker dose.

• atenolol

  Monitor Closely (2)atenolol and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  atenolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)atenolol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• avanafil

  Monitor Closely (2)avanafil increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
  
  avanafil increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• balsalazide

  Minor (1)hydrochlorothiazide will increase the level or effect of balsalazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• beclomethasone, inhaled

  Monitor Closely (1)beclomethasone, inhaled increases toxicity of hydrochlorothiazide by increasing elimination. Use Caution/Monitor. May increase the hypokalemic effects of thiazide diuretics.

• benazepril

  Monitor Closely (1)benazepril increases toxicity of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Enhanced hypotensive effects; increased risk of nephrotoxicity.

• bendroflumethiazide

  Monitor Closely (2)bendroflumethiazide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and bendroflumethiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)bendroflumethiazide will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• betaxolol

  Monitor Closely (2)betaxolol and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  betaxolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)betaxolol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• birch

  Minor (1)birch increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.

• bismuth subsalicylate

  Monitor Closely (1)bismuth subsalicylate, metoprolol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Blockage of renal prostaglandin synthesis; may cause severe hypertension.

• bisoprolol

  Monitor Closely (2)bisoprolol and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  bisoprolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)bisoprolol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• bitter melon

  Minor (1)bitter melon, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• bretylium

  Monitor Closely (2)metoprolol, bretylium. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Each drug may cause hypotension.
  
  hydrochlorothiazide, bretylium. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Each drug may cause hypotension.

• brimonidine

  Minor (2)brimonidine increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.
  
  brimonidine increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• budesonide

  Minor (1)budesonide, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• bumetanide

  Monitor Closely (2)metoprolol increases and bumetanide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  bumetanide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• buprenorphine, long-acting injection

  Monitor Closely (1)buprenorphine, long-acting injection decreases effects of hydrochlorothiazide by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Opioids can reduce diuretic efficacy by inducing antidiuretic hormone release.

• bupropion

  Monitor Closely (1)bupropion will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• butabarbital

  Monitor Closely (1)butabarbital decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of butabarbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• butalbital

  Monitor Closely (1)butalbital decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of butalbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• calcifediol

  Monitor Closely (1)hydrochlorothiazide increases toxicity of calcifediol by Other (see comment). Use Caution/Monitor. Comment: Thiazide diuretics may increase serum calcium by decreasing urinary calcium excretion.

• calcitriol topical

  Minor (1)calcitriol topical, hydrochlorothiazide. Either increases toxicity of the other by pharmacodynamic synergism. Minor/Significance Unknown. Potential additive hypercalcemia.

• calcium acetate

  Monitor Closely (1)calcium acetate decreases effects of metoprolol by unspecified interaction mechanism. Use Caution/Monitor.Minor (1)hydrochlorothiazide increases levels of calcium acetate by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• calcium carbonate

  Monitor Closely (2)calcium carbonate decreases effects of metoprolol by unspecified interaction mechanism. Use Caution/Monitor.
  
  calcium carbonate decreases levels of metoprolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.Minor (1)hydrochlorothiazide increases levels of calcium carbonate by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• calcium chloride

  Monitor Closely (1)calcium chloride decreases effects of metoprolol by unspecified interaction mechanism. Use Caution/Monitor.Minor (1)hydrochlorothiazide increases levels of calcium chloride by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• calcium citrate

  Monitor Closely (1)calcium citrate decreases effects of metoprolol by unspecified interaction mechanism. Use Caution/Monitor.Minor (1)hydrochlorothiazide increases levels of calcium citrate by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• calcium gluconate

  Monitor Closely (1)calcium gluconate decreases effects of metoprolol by unspecified interaction mechanism. Use Caution/Monitor.Minor (1)hydrochlorothiazide increases levels of calcium gluconate by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• candesartan

  Monitor Closely (3)candesartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  candesartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol, candesartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• captopril

  Monitor Closely (1)captopril, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Both drugs lower blood pressure. Increased risk of nephrotoxicity. Monitor blood pressure and renal function.

• carbamazepine

  Serious - Use Alternative (1)carbamazepine, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased risk of systemic hyponatremia.

• carbenoxolone

  Monitor Closely (2)metoprolol increases and carbenoxolone decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydrochlorothiazide and carbenoxolone both decrease serum potassium. Use Caution/Monitor.Minor (1)hydrochlorothiazide, carbenoxolone. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive hypokalemic effects.

• carbidopa

  Monitor Closely (2)carbidopa increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Therapy with carbidopa, given with or without levodopa or carbidopa-levodopa combination products, is started, dosage adjustment of the antihypertensive drug may be required.
  
  carbidopa increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Therapy with carbidopa, given with or without levodopa or carbidopa-levodopa combination products, is started, dosage adjustment of the antihypertensive drug may be required.

• carvedilol

  Monitor Closely (2)carvedilol and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  carvedilol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)carvedilol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• cefadroxil

  Minor (1)cefadroxil will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• cefamandole

  Minor (1)cefamandole will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• cefpirome

  Minor (1)cefpirome will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• cefprozil

  Monitor Closely (1)hydrochlorothiazide will increase the level or effect of cefprozil by acidic (anionic) drug competition for renal tubular clearance. Use Caution/Monitor.Minor (1)cefprozil will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• ceftibuten

  Minor (1)ceftibuten will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• celecoxib

  Monitor Closely (4)celecoxib decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and celecoxib both increase serum potassium. Use Caution/Monitor.
  
  celecoxib increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  celecoxib will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of celecoxib by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• celiprolol

  Monitor Closely (3)celiprolol and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  celiprolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydrochlorothiazide decreases levels of celiprolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.Serious - Use Alternative (1)celiprolol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• cephalexin

  Minor (1)cephalexin will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• cevimeline

  Minor (1)cevimeline increases effects of metoprolol by unspecified interaction mechanism. Minor/Significance Unknown.

• chloroquine

  Monitor Closely (1)chloroquine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• chlorothiazide

  Monitor Closely (2)chlorothiazide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and chlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)chlorothiazide will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• chlorpromazine

  Serious - Use Alternative (1)metoprolol, chlorpromazine. Either increases levels of the other by decreasing metabolism. Contraindicated. Not all beta blockers share this interaction (e.g., atenolol, nadolol, sotalol do not interact).

• chlorpropamide

  Minor (2)hydrochlorothiazide will increase the level or effect of chlorpropamide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.
  
  hydrochlorothiazide decreases effects of chlorpropamide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• chlorthalidone

  Monitor Closely (2)metoprolol increases and chlorthalidone decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  chlorthalidone and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)chlorthalidone will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• cholestyramine

  Monitor Closely (1)cholestyramine decreases levels of hydrochlorothiazide by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.

• choline magnesium trisalicylate

  Monitor Closely (2)choline magnesium trisalicylate decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and choline magnesium trisalicylate both increase serum potassium. Use Caution/Monitor.

• cimetidine

  Monitor Closely (1)cimetidine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• ciprofloxacin

  Minor (1)ciprofloxacin increases levels of metoprolol by decreasing metabolism. Minor/Significance Unknown. Ciprofloxacin may increase metoprolol plasma concentrations however mechanism is unknown. Further clinical evidence is needed but it may be appropriate to monitor patients during concomitant therapy with ciprofloxacin.

• citalopram

  Monitor Closely (2)citalopram increases levels of metoprolol by decreasing metabolism. Use Caution/Monitor. Increased metoprolol plasma levels have been associated with decreased cardioselectivity.
  
  hydrochlorothiazide, citalopram. pharmacodynamic synergism. Use Caution/Monitor. Possible additive hyponatremia.

• clevidipine

  Monitor Closely (1)metoprolol and clevidipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• clonidine

  Monitor Closely (2)clonidine, metoprolol. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive sympatholytic action may worsen sinus node dysfunction and atrioventricular (AV) block.
  
  metoprolol, clonidine. Mechanism: pharmacodynamic synergism. Modify Therapy/Monitor Closely. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.Serious - Use Alternative (1)clonidine, metoprolol. Either increases toxicity of the other by unspecified interaction mechanism. Avoid or Use Alternate Drug. Can increase risk of bradycardia.

• cobicistat

  Monitor Closely (1)cobicistat will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• cocaine topical

  Minor (1)metoprolol increases effects of cocaine topical by pharmacodynamic synergism. Minor/Significance Unknown. Risk of angina.

• colestipol

  Minor (1)colestipol decreases levels of hydrochlorothiazide by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

• cornsilk

  Monitor Closely (1)cornsilk increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of hypokalemia (theoretical interaction).Minor (1)cornsilk increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• corticotropin

  Monitor Closely (1)corticotropin increases toxicity of hydrochlorothiazide by increasing renal clearance. Use Caution/Monitor. May enhance hypokalemic effect of thiazide diuretics.

• cortisone

  Minor (1)cortisone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• cosyntropin

  Minor (1)cosyntropin, hydrochlorothiazide. pharmacodynamic synergism. Minor/Significance Unknown. Possible enhanced electrolyte loss.

• cyclopenthiazide

  Monitor Closely (2)metoprolol increases and cyclopenthiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  cyclopenthiazide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)cyclopenthiazide will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• cyclophosphamide

  Serious - Use Alternative (1)hydrochlorothiazide increases toxicity of cyclophosphamide by decreasing renal clearance. Avoid or Use Alternate Drug. Increased myelosuppressive effects.

• cyclosporine

  Monitor Closely (1)cyclosporine increases toxicity of hydrochlorothiazide by unspecified interaction mechanism. Use Caution/Monitor. Coadministration of hydrochlorothiazide with cyclosporine may increase the risk of hypermagnesemia, hyperuricemia, and possible nephrotoxicity.Serious - Use Alternative (1)cyclosporine, hydrochlorothiazide. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased risk of systemic hyponatremia.

• dacomitinib

  Serious - Use Alternative (1)dacomitinib will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid use with CYP2D6 substrates where minimal increases in concentration of the CYP2D6 substrate may lead to serious or life-threatening toxicities.

• darifenacin

  Monitor Closely (1)darifenacin will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• darunavir

  Monitor Closely (1)darunavir will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• dasiglucagon

  Monitor Closely (1)metoprolol decreases effects of dasiglucagon by unknown mechanism. Use Caution/Monitor. Dasiglucagon may stimulate catecholamine release; whereas beta blockers may inhibit catecholamines released in response to dasiglucagon. Coadministration may also transiently increase pulse and BP.

• deflazacort

  Monitor Closely (1)hydrochlorothiazide and deflazacort both decrease serum potassium. Use Caution/Monitor.Minor (1)deflazacort, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• desflurane

  Monitor Closely (1)desflurane, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• desvenlafaxine

  Monitor Closely (1)desvenlafaxine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Desvenlafaxine inhibits CYP2D6; with higher desvenlafaxine doses (ie, 400 mg) decrease the CYP2D6 substrate dose by up to 50%; no dosage adjustment needed with desvenlafaxine doses <100 mg

• dexamethasone

  Minor (1)dexamethasone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• diazepam

  Minor (1)metoprolol increases effects of diazepam by decreasing metabolism. Minor/Significance Unknown.

• diazoxide

  Monitor Closely (1)hydrochlorothiazide increases toxicity of diazoxide by unspecified interaction mechanism. Use Caution/Monitor. May enhance hyperglycemic effects of diazoxide.Minor (1)diazoxide, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperglycemia.

• dichlorphenamide

  Monitor Closely (1)dichlorphenamide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• diclofenac

  Monitor Closely (3)diclofenac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and diclofenac both increase serum potassium. Use Caution/Monitor.
  
  diclofenac decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.Minor (1)hydrochlorothiazide will increase the level or effect of diclofenac by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• dicloxacillin

  Monitor Closely (1)dicloxacillin, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• diflunisal

  Monitor Closely (3)diflunisal decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and diflunisal both increase serum potassium. Use Caution/Monitor.
  
  diflunisal increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of diflunisal by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• digoxin

  Monitor Closely (5)hydrochlorothiazide increases effects of digoxin by pharmacodynamic synergism. Use Caution/Monitor. Hypokalemia increases digoxin effects.
  
  metoprolol and digoxin both increase serum potassium. Use Caution/Monitor.
  
  digoxin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol increases effects of digoxin by pharmacodynamic synergism. Use Caution/Monitor. Enhanced bradycardia.
  
  digoxin will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.Serious - Use Alternative (1)digoxin increases toxicity of metoprolol by unspecified interaction mechanism. Avoid or Use Alternate Drug. Can increase risk of bradycardia.

• dihydroergotamine

  Minor (1)dihydroergotamine, metoprolol. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive vasospasm.

• dihydroergotamine intranasal

  Minor (1)dihydroergotamine intranasal, metoprolol. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive vasospasm.

• diltiazem

  Monitor Closely (1)metoprolol and diltiazem both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.Serious - Use Alternative (1)diltiazem, metoprolol. Either increases toxicity of the other by unspecified interaction mechanism. Avoid or Use Alternate Drug. Can increase risk of bradycardia.

• diphenhydramine

  Monitor Closely (1)diphenhydramine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• dipyridamole

  Minor (1)dipyridamole, metoprolol. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of bradycardia.

• dobutamine

  Monitor Closely (3)metoprolol increases and dobutamine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dobutamine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol decreases effects of dobutamine by pharmacodynamic antagonism. Use Caution/Monitor.Minor (1)dobutamine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• dofetilide

  Monitor Closely (1)dofetilide will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.Serious - Use Alternative (1)hydrochlorothiazide increases levels of dofetilide by decreasing renal clearance. Contraindicated. Risk of prolonged QTc interval.

• dopexamine

  Monitor Closely (3)metoprolol increases and dopexamine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dopexamine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol decreases effects of dopexamine by pharmacodynamic antagonism. Use Caution/Monitor.Minor (1)dopexamine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• doxazosin

  Monitor Closely (1)doxazosin and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• dronedarone

  Monitor Closely (1)dronedarone will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• drospirenone

  Monitor Closely (2)drospirenone increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.
  
  metoprolol and drospirenone both increase serum potassium. Modify Therapy/Monitor Closely.

• duloxetine

  Monitor Closely (1)duloxetine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• eliglustat

  Monitor Closely (1)eliglustat increases levels of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the concomitant drug and titrate to clinical effect.

• elvitegravir/cobicistat/emtricitabine/tenofovir DF

  Serious - Use Alternative (1)elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Cobicistat is a CYP2D6 inhibitor; caution with CYP2D6 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.

• empagliflozin

  Monitor Closely (1)empagliflozin, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration of empagliflozin with diuretics results in increased urine volume and frequency of voids, which might enhance the potential for volume depletion.

• ephedrine

  Monitor Closely (3)metoprolol increases and ephedrine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  ephedrine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol decreases effects of ephedrine by pharmacodynamic antagonism. Use Caution/Monitor.Minor (1)ephedrine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• epinephrine

  Monitor Closely (3)epinephrine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and epinephrine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol decreases effects of epinephrine by pharmacodynamic antagonism. Use Caution/Monitor.Minor (1)epinephrine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• epinephrine racemic

  Monitor Closely (3)metoprolol decreases effects of epinephrine racemic by pharmacodynamic antagonism. Use Caution/Monitor.
  
  metoprolol increases and epinephrine racemic decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  epinephrine racemic and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)epinephrine racemic, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• epoprostenol

  Minor (1)epoprostenol increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown. Additive hypotensive effects.

• eprosartan

  Monitor Closely (3)eprosartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  eprosartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol, eprosartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• escitalopram

  Minor (1)escitalopram increases levels of metoprolol by decreasing metabolism. Minor/Significance Unknown.

• esmolol

  Monitor Closely (2)esmolol and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  esmolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)esmolol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• ethacrynic acid

  Monitor Closely (2)metoprolol increases and ethacrynic acid decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  ethacrynic acid and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• ether

  Monitor Closely (1)metoprolol, ether. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Both beta blockers and ether depress the myocardium; consider lowering beta blocker dose if ether used for anesthesia.

• etodolac

  Monitor Closely (3)etodolac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  etodolac decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and etodolac both increase serum potassium. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of etodolac by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• etomidate

  Monitor Closely (1)etomidate, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• exenatide injectable solution

  Monitor Closely (1)hydrochlorothiazide decreases effects of exenatide injectable solution by pharmacodynamic antagonism. Use Caution/Monitor. Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Monitor glycemic control especially when initiating, discontinuing, or increasing thiazide diuretic dose.

• exenatide injectable suspension

  Monitor Closely (1)hydrochlorothiazide decreases effects of exenatide injectable suspension by pharmacodynamic antagonism. Use Caution/Monitor. Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Monitor glycemic control especially when initiating, discontinuing, or increasing thiazide diuretic dose.

• fedratinib

  Monitor Closely (1)fedratinib will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.

• felodipine

  Monitor Closely (1)metoprolol and felodipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• fenbufen

  Monitor Closely (1)metoprolol and fenbufen both increase serum potassium. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of fenbufen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• fenoldopam

  Minor (1)fenoldopam increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown. Additive hypotensive effects.

• fenoprofen

  Monitor Closely (3)fenoprofen decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and fenoprofen both increase serum potassium. Use Caution/Monitor.
  
  fenoprofen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of fenoprofen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• fentanyl

  Monitor Closely (1)fentanyl decreases effects of hydrochlorothiazide by Other (see comment). Modify Therapy/Monitor Closely. Comment: Fentanyl can reduce the efficacy of diuretics by inducing antidiuretic hormone release. Fentanyl may also lead to acute urinary retention by causing bladder sphincter spasm (particularly in men with enlarged prostates).

• fentanyl intranasal

  Monitor Closely (1)fentanyl intranasal decreases effects of hydrochlorothiazide by Other (see comment). Modify Therapy/Monitor Closely. Comment: Fentanyl can reduce the efficacy of diuretics by inducing antidiuretic hormone release. Fentanyl may also lead to acute urinary retention by causing bladder sphincter spasm (particularly in men with enlarged prostates).

• fentanyl transdermal

  Monitor Closely (1)fentanyl transdermal decreases effects of hydrochlorothiazide by Other (see comment). Modify Therapy/Monitor Closely. Comment: Fentanyl can reduce the efficacy of diuretics by inducing antidiuretic hormone release. Fentanyl may also lead to acute urinary retention by causing bladder sphincter spasm (particularly in men with enlarged prostates).

• fentanyl transmucosal

  Monitor Closely (1)fentanyl transmucosal decreases effects of hydrochlorothiazide by Other (see comment). Modify Therapy/Monitor Closely. Comment: Fentanyl can reduce the efficacy of diuretics by inducing antidiuretic hormone release. Fentanyl may also lead to acute urinary retention by causing bladder sphincter spasm (particularly in men with enlarged prostates).

• fexinidazole

  Serious - Use Alternative (1)fexinidazole, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration of fexinidazole with drugs known to induce bradycardia. .

• fingolimod

  Monitor Closely (1)metoprolol increases effects of fingolimod by pharmacodynamic synergism. Use Caution/Monitor. Both medications decrease heart rate. Monitor patients on concomitant therapy, particularly in the first 6 hours after fingolimod is initiated or after a treatment interruption of at least two weeks, for bradycardia and atrioventricular block. To identify underlying risk factors of bradycardia and AV block, obtain a new or recent ECG in patients using beta-blockers prior to starting fingolimod.

• fludrocortisone

  Minor (1)fludrocortisone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• fluoxetine

  Serious - Use Alternative (1)fluoxetine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• flurbiprofen

  Monitor Closely (3)flurbiprofen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and flurbiprofen both increase serum potassium. Use Caution/Monitor.
  
  flurbiprofen decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.Minor (1)hydrochlorothiazide will increase the level or effect of flurbiprofen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• fo-ti

  Minor (1)fo-ti increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia (theoretical).

• folic acid

  Minor (1)hydrochlorothiazide decreases levels of folic acid by increasing renal clearance. Minor/Significance Unknown.

• formoterol

  Monitor Closely (3)formoterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol decreases effects of formoterol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  metoprolol increases and formoterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)formoterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• forskolin

  Minor (2)forskolin increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.
  
  forskolin increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.

• furosemide

  Monitor Closely (2)metoprolol increases and furosemide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  furosemide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• ganciclovir

  Minor (1)hydrochlorothiazide will increase the level or effect of ganciclovir by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• gentamicin

  Monitor Closely (2)metoprolol increases and gentamicin decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydrochlorothiazide and gentamicin both decrease serum potassium. Use Caution/Monitor.

• givosiran

  Serious - Use Alternative (1)givosiran will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP2D6 substrates with givosiran. If unavoidable, decrease the CYP2D6 substrate dosage in accordance with approved product labeling.

• glimepiride

  Minor (1)hydrochlorothiazide decreases effects of glimepiride by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• glipizide

  Minor (1)hydrochlorothiazide decreases effects of glipizide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• glucagon

  Monitor Closely (1)glucagon decreases toxicity of metoprolol by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Coadministration of glucagon with beta-blockers may have transiently increased pulse and blood pressure.

• glucagon intranasal

  Monitor Closely (1)glucagon intranasal decreases toxicity of metoprolol by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Coadministration of glucagon with beta-blockers may have transiently increased pulse and blood pressure.

• glyburide

  Minor (1)hydrochlorothiazide decreases effects of glyburide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• goldenrod

  Minor (1)goldenrod increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.

• guanfacine

  Minor (1)metoprolol, guanfacine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.

• haloperidol

  Monitor Closely (1)haloperidol will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• hydralazine

  Monitor Closely (1)hydralazine increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• hydrochlorothiazide

  Monitor Closely (2)hydrochlorothiazide, metoprolol. Either increases toxicity of the other by Other (see comment). Modify Therapy/Monitor Closely. Comment: May cause idiosyncratic reaction, resulting in acute transient myopia and acute angle-closure glaucoma, which can lead to permanent vision loss.
  
  metoprolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• hydrocortisone

  Minor (1)hydrocortisone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• ibuprofen

  Monitor Closely (3)ibuprofen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and ibuprofen both increase serum potassium. Use Caution/Monitor.
  
  ibuprofen decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.Minor (1)hydrochlorothiazide will increase the level or effect of ibuprofen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• ibuprofen IV

  Monitor Closely (4)ibuprofen IV decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and ibuprofen IV both increase serum potassium. Use Caution/Monitor.
  
  hydrochlorothiazide will increase the level or effect of ibuprofen IV by acidic (anionic) drug competition for renal tubular clearance. Use Caution/Monitor.
  
  ibuprofen IV increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor. NSAIDs may decrease the therapeutic effects of thiazide-like diuretics; may also enhance nephrotoxic effects.

• imaging agents (gadolinium)

  Minor (1)metoprolol, imaging agents (gadolinium). Mechanism: unknown. Minor/Significance Unknown. Increased risk of anaphylaxis from contrast media.

• imatinib

  Monitor Closely (1)imatinib will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• indacaterol, inhaled

  Monitor Closely (3)hydrochlorothiazide, indacaterol, inhaled. serum potassium. Use Caution/Monitor. Combination may increase risk of hypokalemia.
  
  indacaterol, inhaled, metoprolol. Other (see comment). Use Caution/Monitor. Comment: Beta-blockers and indacaterol may interfere with the effect of each other when administered concurrently. Beta-blockers may produce severe bronchospasm in COPD patients. Therefore, patients with COPD should not normally be treated with beta-blockers. However, under certain circumstances, e.g. as prophylaxis after myocardial infarction, there may be no acceptable alternatives to the use of beta-blockers in patients with COPD. In this setting, cardioselective beta-blockers could be considered, although they should be administered with caution.
  
  indacaterol, inhaled, hydrochlorothiazide. Other (see comment). Use Caution/Monitor. Comment: Caution is advised in the coadministration of indacaterol neohaler with non-potassium-sparing diuretics.

• indapamide

  Monitor Closely (2)metoprolol increases and indapamide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydrochlorothiazide and indapamide both decrease serum potassium. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of indapamide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• indomethacin

  Monitor Closely (3)indomethacin decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and indomethacin both increase serum potassium. Use Caution/Monitor.
  
  indomethacin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of indomethacin by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• insulin aspart

  Minor (1)hydrochlorothiazide decreases effects of insulin aspart by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• insulin degludec

  Monitor Closely (2)metoprolol, insulin degludec. Other (see comment). Modify Therapy/Monitor Closely. Comment: Beta-blockers may either increase or decrease the blood glucose lowering effect of insulin; beta-blockers can prolong hypoglycemia (interference with glycogenolysis) or cause hyperglycemia (insulin secretion inhibited).
  
  hydrochlorothiazide decreases effects of insulin degludec by Other (see comment). Use Caution/Monitor. Comment: Diuretics may cause hyperglycemia and glycosuria in patients with diabetes mellitus, possibly by diuretic-induced hpokalemia.

• insulin degludec/insulin aspart

  Monitor Closely (2)metoprolol, insulin degludec/insulin aspart. Other (see comment). Modify Therapy/Monitor Closely. Comment: Beta-blockers may either increase or decrease the blood glucose lowering effect of insulin; beta-blockers can prolong hypoglycemia (interference with glycogenolysis) or cause hyperglycemia (insulin secretion inhibited).
  
  hydrochlorothiazide decreases effects of insulin degludec/insulin aspart by Other (see comment). Use Caution/Monitor. Comment: Diuretics may cause hyperglycemia and glycosuria in patients with diabetes mellitus, possibly by diuretic-induced hpokalemia.

• insulin detemir

  Minor (1)hydrochlorothiazide decreases effects of insulin detemir by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• insulin glargine

  Minor (1)hydrochlorothiazide decreases effects of insulin glargine by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• insulin glulisine

  Minor (1)hydrochlorothiazide decreases effects of insulin glulisine by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• insulin inhaled

  Monitor Closely (2)metoprolol, insulin inhaled. Other (see comment). Modify Therapy/Monitor Closely. Comment: Beta-blockers may either increase or decrease the blood glucose lowering effect of insulin; beta-blockers can prolong hypoglycemia (interference with glycogenolysis) or cause hyperglycemia (insulin secretion inhibited).
  
  hydrochlorothiazide decreases effects of insulin inhaled by Other (see comment). Use Caution/Monitor. Comment: Diuretics may cause hyperglycemia and glycosuria in patients with diabetes mellitus, possibly by diuretic-induced hpokalemia.

• insulin lispro

  Minor (1)hydrochlorothiazide decreases effects of insulin lispro by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• insulin NPH

  Minor (1)hydrochlorothiazide decreases effects of insulin NPH by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• insulin regular human

  Minor (1)hydrochlorothiazide decreases effects of insulin regular human by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• irbesartan

  Monitor Closely (3)irbesartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  irbesartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol, irbesartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• isocarboxazid

  Serious - Use Alternative (1)isocarboxazid, hydrochlorothiazide. Other (see comment). Contraindicated. Comment: Additive hypotensive effects may be seen when MAOI's are combined with antihypertensives.

• isoproterenol

  Monitor Closely (3)metoprolol increases and isoproterenol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  isoproterenol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol decreases effects of isoproterenol by pharmacodynamic antagonism. Use Caution/Monitor.Minor (1)isoproterenol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• isradipine

  Monitor Closely (1)metoprolol and isradipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• ivabradine

  Monitor Closely (1)ivabradine, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Most patients receiving ivabradine will also be treated with a beta-blocker. The risk of bradycardia increases with coadministration of drugs that slow heart rate (eg, digoxin, amiodarone, beta-blockers). Monitor heart rate in patients taking ivabradine with other negative chronotropes.

• juniper

  Monitor Closely (1)juniper, hydrochlorothiazide. Other (see comment). Use Caution/Monitor. Comment: Juniper may potentiate or interfere with diuretic therapy. Juniper has diuretic effects, but may cause kidney damage at large doses.

• ketamine

  Monitor Closely (1)ketamine, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• ketoprofen

  Monitor Closely (3)ketoprofen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  ketoprofen decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and ketoprofen both increase serum potassium. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of ketoprofen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• ketorolac

  Monitor Closely (3)metoprolol and ketorolac both increase serum potassium. Use Caution/Monitor.
  
  ketorolac decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  ketorolac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of ketorolac by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• ketorolac intranasal

  Monitor Closely (3)ketorolac intranasal decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  ketorolac intranasal increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor. .
  
  metoprolol and ketorolac intranasal both increase serum potassium. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of ketorolac intranasal by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• L-methylfolate

  Minor (1)hydrochlorothiazide decreases levels of L-methylfolate by increasing renal clearance. Minor/Significance Unknown.

• labetalol

  Monitor Closely (2)labetalol and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  labetalol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)labetalol and metoprolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• levalbuterol

  Monitor Closely (3)metoprolol decreases effects of levalbuterol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  metoprolol increases and levalbuterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  levalbuterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)levalbuterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• levobetaxolol

  Minor (1)levobetaxolol increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• levodopa

  Monitor Closely (2)levodopa increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Consider decreasing dosage of antihypertensive agent.
  
  levodopa increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Consider decreasing dosage of antihypertensive agent.

• lily of the valley

  Monitor Closely (1)hydrochlorothiazide increases toxicity of lily of the valley by Other (see comment). Use Caution/Monitor. Comment: Increased risk of cardiac toxicity due to K+ depletion.

• liraglutide

  Monitor Closely (1)hydrochlorothiazide decreases effects of liraglutide by pharmacodynamic antagonism. Use Caution/Monitor. Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Monitor glycemic control especially when initiating, discontinuing, or increasing thiazide diuretic dose.

• lithium

  Monitor Closely (1)hydrochlorothiazide increases toxicity of lithium by decreasing elimination. Use Caution/Monitor.

• lofexidine

  Serious - Use Alternative (2)lofexidine, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration with other drugs that decrease pulse or blood pressure to mitigate risk of excessive bradycardia and hypotension.
  
  lofexidine, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration with other drugs that decrease pulse or blood pressure to mitigate risk of excessive bradycardia and hypotension.

• lorcaserin

  Monitor Closely (1)lorcaserin will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• lornoxicam

  Monitor Closely (3)metoprolol and lornoxicam both increase serum potassium. Use Caution/Monitor.
  
  lornoxicam increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  lornoxicam decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.Minor (1)hydrochlorothiazide will increase the level or effect of lornoxicam by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• losartan

  Monitor Closely (3)losartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  losartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol, losartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• lumefantrine

  Serious - Use Alternative (1)lumefantrine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• lurasidone

  Monitor Closely (2)lurasidone increases effects of metoprolol by Other (see comment). Use Caution/Monitor. Comment: Potential for increased risk of hypotension with concurrent use. Monitor blood pressure and adjust dose of antihypertensive agent as needed.
  
  lurasidone increases effects of hydrochlorothiazide by Other (see comment). Use Caution/Monitor. Comment: Potential for increased risk of hypotension with concurrent use. Monitor blood pressure and adjust dose of antihypertensive agent as needed.

• magnesium chloride

  Minor (1)hydrochlorothiazide decreases levels of magnesium chloride by increasing renal clearance. Minor/Significance Unknown.

• magnesium citrate

  Minor (1)hydrochlorothiazide decreases levels of magnesium citrate by increasing renal clearance. Minor/Significance Unknown.

• magnesium hydroxide

  Minor (1)hydrochlorothiazide decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

• magnesium oxide

  Minor (1)hydrochlorothiazide decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

• magnesium sulfate

  Minor (1)hydrochlorothiazide decreases levels of magnesium sulfate by increasing renal clearance. Minor/Significance Unknown.

• maitake

  Monitor Closely (1)maitake increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of hypokalemia (theoretical interaction).Minor (1)maitake increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• maraviroc

  Monitor Closely (1)maraviroc will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• marijuana

  Monitor Closely (1)marijuana will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• mavacamten

  Serious - Use Alternative (1)metoprolol, mavacamten. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Expect additive negative inotropic effects of mavacamten and other drugs that reduce cardiac contractility.

• meclofenamate

  Monitor Closely (3)meclofenamate decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and meclofenamate both increase serum potassium. Use Caution/Monitor.
  
  meclofenamate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of meclofenamate by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• mefenamic acid

  Monitor Closely (3)mefenamic acid increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and mefenamic acid both increase serum potassium. Use Caution/Monitor.
  
  mefenamic acid decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.Minor (1)hydrochlorothiazide will increase the level or effect of mefenamic acid by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• mefloquine

  Monitor Closely (1)mefloquine increases levels of metoprolol by decreasing metabolism. Use Caution/Monitor. Risk of arrhythmia.

• meloxicam

  Monitor Closely (3)meloxicam decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and meloxicam both increase serum potassium. Use Caution/Monitor.
  
  meloxicam increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of meloxicam by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• memantine

  Minor (1)hydrochlorothiazide will increase the level or effect of memantine by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• mesalamine

  Minor (1)hydrochlorothiazide will increase the level or effect of mesalamine by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• metaproterenol

  Monitor Closely (3)metoprolol increases and metaproterenol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metaproterenol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol decreases effects of metaproterenol by pharmacodynamic antagonism. Use Caution/Monitor.Minor (1)metaproterenol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• metformin

  Minor (2)hydrochlorothiazide will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
  
  hydrochlorothiazide decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• methotrexate

  Minor (1)hydrochlorothiazide increases toxicity of methotrexate by decreasing elimination. Minor/Significance Unknown. Increased myelosuppression.

• methoxsalen

  Monitor Closely (1)methoxsalen, hydrochlorothiazide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive photosensitizing effects.

• methyclothiazide

  Monitor Closely (1)metoprolol increases and methyclothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor. .

• methyl aminolevulinate

  Serious - Use Alternative (1)hydrochlorothiazide, methyl aminolevulinate. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Each drug may increase the photosensitizing effect of the other.

• methylphenidate transdermal

  Monitor Closely (1)methylphenidate transdermal decreases effects of hydrochlorothiazide by anti-hypertensive channel blocking. Use Caution/Monitor.

• methylprednisolone

  Minor (1)methylprednisolone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• metipranolol ophthalmic

  Minor (1)metipranolol ophthalmic increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• metolazone

  Monitor Closely (2)metoprolol increases and metolazone decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydrochlorothiazide and metolazone both decrease serum potassium. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of metolazone by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• metoprolol

  Monitor Closely (2)hydrochlorothiazide, metoprolol. Either increases toxicity of the other by Other (see comment). Modify Therapy/Monitor Closely. Comment: May cause idiosyncratic reaction, resulting in acute transient myopia and acute angle-closure glaucoma, which can lead to permanent vision loss.
  
  metoprolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• midodrine

  Minor (1)hydrochlorothiazide will increase the level or effect of midodrine by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• miglitol

  Minor (1)hydrochlorothiazide decreases effects of miglitol by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• minoxidil

  Minor (1)hydrochlorothiazide increases effects of minoxidil by pharmacodynamic synergism. Minor/Significance Unknown.

• mirabegron

  Monitor Closely (1)mirabegron will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• mometasone inhaled

  Monitor Closely (1)mometasone inhaled increases toxicity of hydrochlorothiazide by Other (see comment). Use Caution/Monitor. Comment: Corticosteroids may increase hypokalemic effect of loop diuretics.

• moxisylyte

  Monitor Closely (1)moxisylyte and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• mycophenolate

  Monitor Closely (1)hydrochlorothiazide will increase the level or effect of mycophenolate by acidic (anionic) drug competition for renal tubular clearance. Use Caution/Monitor.

• nabumetone

  Monitor Closely (3)nabumetone increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  nabumetone decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and nabumetone both increase serum potassium. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of nabumetone by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• nadolol

  Monitor Closely (2)metoprolol and nadolol both increase serum potassium. Use Caution/Monitor.
  
  nadolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)metoprolol and nadolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• nafcillin

  Monitor Closely (1)nafcillin, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• naproxen

  Monitor Closely (3)metoprolol and naproxen both increase serum potassium. Use Caution/Monitor.
  
  naproxen decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  naproxen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of naproxen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• nateglinide

  Minor (1)hydrochlorothiazide decreases effects of nateglinide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• nebivolol

  Monitor Closely (2)nebivolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and nebivolol both increase serum potassium. Use Caution/Monitor.Serious - Use Alternative (1)metoprolol and nebivolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• neostigmine

  Minor (1)metoprolol, neostigmine. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive bradycardia.

• nicardipine

  Monitor Closely (1)metoprolol and nicardipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• nifedipine

  Monitor Closely (1)metoprolol and nifedipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• nilotinib

  Monitor Closely (1)nilotinib will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• nisoldipine

  Monitor Closely (1)metoprolol and nisoldipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• nitroglycerin rectal

  Monitor Closely (2)nitroglycerin rectal, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Observe for possible additive hypotensive effects during concomitant use. .
  
  nitroglycerin rectal, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Beta-blockers blunt the reflex tachycardia produced by nitroglycerin without preventing its hypotensive effects. If beta-blockers are used with nitroglycerin in patients with angina pectoris, additional hypotensive effects may occur.

• noni juice

  Minor (2)metoprolol and noni juice both increase serum potassium. Minor/Significance Unknown.
  
  noni juice increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Minor/Significance Unknown.

• norepinephrine

  Monitor Closely (3)metoprolol decreases effects of norepinephrine by pharmacodynamic antagonism. Use Caution/Monitor.
  
  norepinephrine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and norepinephrine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (2)hydrochlorothiazide decreases effects of norepinephrine by pharmacodynamic antagonism. Minor/Significance Unknown. May decrease responsiveness to norepinephrine but not enough to preclude effectiveness of the pressor agent therapeutic use.
  
  norepinephrine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• octacosanol

  Minor (2)octacosanol increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.
  
  octacosanol increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• ofloxacin

  Minor (1)hydrochlorothiazide will increase the level or effect of ofloxacin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• oliceridine

  Monitor Closely (1)oliceridine decreases effects of hydrochlorothiazide by Other (see comment). Use Caution/Monitor. Comment: Opioids can reduce the efficacy of diuretics by inducing the release of antidiuretic hormone. Monitor for signs of diminished diuresis and/or effects on blood pressure and increase dosage of the diuretic as needed. .

• olmesartan

  Monitor Closely (3)metoprolol, olmesartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.
  
  olmesartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  olmesartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• olodaterol inhaled

  Monitor Closely (1)hydrochlorothiazide and olodaterol inhaled both decrease serum potassium. Use Caution/Monitor.

• oxaprozin

  Monitor Closely (3)metoprolol and oxaprozin both increase serum potassium. Use Caution/Monitor.
  
  oxaprozin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  oxaprozin decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.Minor (1)hydrochlorothiazide will increase the level or effect of oxaprozin by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• oxazepam

  Minor (1)metoprolol increases effects of oxazepam by decreasing metabolism. Minor/Significance Unknown.

• oxymetazoline topical

  Monitor Closely (1)oxymetazoline topical increases and metoprolol decreases sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• panobinostat

  Monitor Closely (1)panobinostat will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Panobinostat can increase the levels and effects of sensitive CYP2D6 substrates or those with a narrow therapeutic index CYP2D6.

• parecoxib

  Monitor Closely (4)parecoxib decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and parecoxib both increase serum potassium. Use Caution/Monitor.
  
  parecoxib increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  parecoxib will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of parecoxib by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• paroxetine

  Serious - Use Alternative (1)paroxetine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• patiromer

  Minor (1)patiromer, metoprolol. cation binding in GI tract. Minor/Significance Unknown. No observed clinically important interaction. No separation of dosing required.

• peginterferon alfa 2b

  Monitor Closely (1)peginterferon alfa 2b, metoprolol. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate.

• penbutolol

  Monitor Closely (2)metoprolol and penbutolol both increase serum potassium. Use Caution/Monitor.
  
  penbutolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)metoprolol and penbutolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• penicillin G aqueous

  Monitor Closely (1)penicillin G aqueous, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.Minor (1)hydrochlorothiazide increases levels of penicillin G aqueous by decreasing renal clearance. Minor/Significance Unknown.

• penicillin VK

  Minor (1)hydrochlorothiazide increases levels of penicillin VK by decreasing renal clearance. Minor/Significance Unknown.

• pentobarbital

  Monitor Closely (1)pentobarbital decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of pentobarbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• perphenazine

  Monitor Closely (1)perphenazine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• phenobarbital

  Monitor Closely (1)phenobarbital decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of phenobarbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• phenoxybenzamine

  Monitor Closely (1)phenoxybenzamine and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• phentolamine

  Monitor Closely (1)phentolamine and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• physostigmine

  Minor (1)metoprolol, physostigmine. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive bradycardia.

• pilocarpine

  Minor (1)pilocarpine increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• pindolol

  Monitor Closely (2)pindolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and pindolol both increase serum potassium. Use Caution/Monitor.Serious - Use Alternative (1)metoprolol and pindolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• pioglitazone

  Minor (1)hydrochlorothiazide decreases effects of pioglitazone by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• piperacillin

  Minor (1)hydrochlorothiazide increases levels of piperacillin by decreasing renal clearance. Minor/Significance Unknown.

• pirbuterol

  Monitor Closely (3)metoprolol decreases effects of pirbuterol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  pirbuterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and pirbuterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)pirbuterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• piroxicam

  Monitor Closely (3)piroxicam increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and piroxicam both increase serum potassium. Use Caution/Monitor.
  
  piroxicam decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.Minor (1)hydrochlorothiazide will increase the level or effect of piroxicam by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• pivmecillinam

  Monitor Closely (1)pivmecillinam, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• ponesimod

  Monitor Closely (1)ponesimod and metoprolol both increase pharmacodynamic synergism. Use Caution/Monitor. Beta-blockers may have additive effects on lowering HR. Consider resting HR before initiating ponesimod in patients on stable dose of beta-blocker. Refer to the ponesimod prescribing information for more dosing information.

• porfimer

  Monitor Closely (1)hydrochlorothiazide, porfimer. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Enhanced photosensitivity.

• potassium acid phosphate

  Monitor Closely (2)potassium acid phosphate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.
  
  metoprolol and potassium acid phosphate both increase serum potassium. Modify Therapy/Monitor Closely.

• potassium chloride

  Monitor Closely (2)metoprolol and potassium chloride both increase serum potassium. Modify Therapy/Monitor Closely.
  
  potassium chloride increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.

• potassium citrate

  Monitor Closely (2)metoprolol and potassium citrate both increase serum potassium. Modify Therapy/Monitor Closely.
  
  potassium citrate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.

• prazosin

  Monitor Closely (1)prazosin and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• prednisolone

  Minor (1)prednisolone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• prednisone

  Minor (1)prednisone, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• primidone

  Monitor Closely (1)primidone decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of primidone. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• probenecid

  Monitor Closely (1)hydrochlorothiazide will increase the level or effect of probenecid by acidic (anionic) drug competition for renal tubular clearance. Use Caution/Monitor.

• procainamide

  Monitor Closely (1)hydrochlorothiazide will increase the level or effect of procainamide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• propafenone

  Monitor Closely (1)propafenone will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent therapy is required, monitor cardiac function carefully, particularly blood pressure. A dosage adjustment for the beta blocker may be required.

• propofol

  Monitor Closely (1)propofol, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• propranolol

  Monitor Closely (2)metoprolol and propranolol both increase serum potassium. Use Caution/Monitor.
  
  propranolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)metoprolol and propranolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• quinacrine

  Monitor Closely (1)quinacrine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• quinidine

  Monitor Closely (1)quinidine will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.Serious - Use Alternative (1)quinidine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. If concurrent therapy required, monitor cardiac function carefully (blood pressure, heart rate). A dosage adjustment may be required for both drugs.

• quinine

  Minor (1)hydrochlorothiazide will increase the level or effect of quinine by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• ranolazine

  Monitor Closely (1)ranolazine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• reishi

  Minor (2)reishi increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.
  
  reishi increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• repaglinide

  Minor (1)hydrochlorothiazide decreases effects of repaglinide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• rifabutin

  Monitor Closely (1)rifabutin decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Enzyme induction effect may continue for up to 3-4 weeks.

• rifampin

  Monitor Closely (1)rifampin decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor.

• rifapentine

  Monitor Closely (1)rifapentine decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor.

• ritonavir

  Monitor Closely (1)ritonavir will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• rivastigmine

  Serious - Use Alternative (1)metoprolol increases toxicity of rivastigmine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Additive bradycardia effect may result in syncope.

• rolapitant

  Monitor Closely (1)rolapitant will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Rolapitant may increase plasma concentrations of CYP2D6 substrates for at least 28 days following rolapitant administration.

• rose hips

  Minor (1)rose hips will increase the level or effect of hydrochlorothiazide by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• rosiglitazone

  Minor (1)hydrochlorothiazide decreases effects of rosiglitazone by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• sacubitril/valsartan

  Monitor Closely (3)sacubitril/valsartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  sacubitril/valsartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  metoprolol, sacubitril/valsartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• salicylates (non-asa)

  Monitor Closely (3)salicylates (non-asa) decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and salicylates (non-asa) both increase serum potassium. Use Caution/Monitor.
  
  salicylates (non-asa) increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of salicylates (non-asa) by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• salmeterol

  Monitor Closely (3)metoprolol decreases effects of salmeterol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  salmeterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and salmeterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)salmeterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• salsalate

  Monitor Closely (3)salsalate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  salsalate decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  metoprolol and salsalate both increase serum potassium. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of salsalate by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• saquinavir

  Monitor Closely (1)saquinavir, metoprolol. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Use alternatives if available. Increased risk of PR prolongation and cardiac arrhythmias.

• saxagliptin

  Minor (1)hydrochlorothiazide decreases effects of saxagliptin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• secobarbital

  Monitor Closely (1)secobarbital decreases levels of metoprolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of secobarbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

• sertraline

  Monitor Closely (1)sertraline will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• sevoflurane

  Monitor Closely (1)sevoflurane, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• shark cartilage

  Monitor Closely (1)hydrochlorothiazide, shark cartilage. Other (see comment). Use Caution/Monitor. Comment: May lead to hypercalcemia (theoretical).

• shepherd's purse

  Minor (2)shepherd's purse, hydrochlorothiazide. Other (see comment). Minor/Significance Unknown. Comment: Theoretically, shepherd's purse may interfere with BP control.
  
  shepherd's purse, metoprolol. Other (see comment). Minor/Significance Unknown. Comment: Theoretically, shepherd's purse may interfere with BP control.

• sildenafil

  Monitor Closely (1)metoprolol increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.

• silodosin

  Monitor Closely (1)silodosin and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• siponimod

  Monitor Closely (1)siponimod, metoprolol. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Caution when siponimod is initiated in patients receiving beta-blocker treatment because of additive effects on lowering heart rate. Temporary interruption of beta-blocker may be needed before initiating siponimod. Beta-blocker treatment can be initiated in patients receiving stable doses of siponimod.

• sitagliptin

  Minor (1)hydrochlorothiazide decreases effects of sitagliptin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• sodium bicarbonate

  Monitor Closely (1)sodium bicarbonate decreases levels of metoprolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

• sodium citrate/citric acid

  Monitor Closely (1)sodium citrate/citric acid decreases levels of metoprolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

• sodium sulfate/?magnesium sulfate/potassium chloride

  Monitor Closely (1)sodium sulfate/?magnesium sulfate/potassium chloride increases toxicity of hydrochlorothiazide by Other (see comment). Use Caution/Monitor. Comment: Coadministration with medications that cause fluid and electrolyte abnormalities may increase the risk of adverse events of seizure, arrhythmias, and renal impairment.

• sodium sulfate/potassium chloride/magnesium sulfate/polyethylene glycol

  Monitor Closely (1)hydrochlorothiazide and sodium sulfate/potassium chloride/magnesium sulfate/polyethylene glycol both decrease serum potassium. Modify Therapy/Monitor Closely.

• sodium sulfate/potassium sulfate/magnesium sulfate

  Monitor Closely (1)sodium sulfate/potassium sulfate/magnesium sulfate increases toxicity of hydrochlorothiazide by Other (see comment). Use Caution/Monitor. Comment: Coadministration with medications that cause fluid and electrolyte abnormalities may increase the risk of adverse events of seizure, arrhythmias, and renal impairment.

• sotalol

  Monitor Closely (2)metoprolol and sotalol both increase serum potassium. Use Caution/Monitor.
  
  sotalol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)metoprolol and sotalol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• spironolactone

  Monitor Closely (2)spironolactone increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.
  
  metoprolol and spironolactone both increase serum potassium. Modify Therapy/Monitor Closely.

• squill

  Serious - Use Alternative (1)hydrochlorothiazide increases toxicity of squill by Other (see comment). Avoid or Use Alternate Drug. Comment: Potassium depletion may enhance toxicity of squill.

• succinylcholine

  Monitor Closely (2)succinylcholine increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and succinylcholine both increase serum potassium. Use Caution/Monitor.

• sulfadiazine

  Minor (1)hydrochlorothiazide increases levels of sulfadiazine by unspecified interaction mechanism. Minor/Significance Unknown.

• sulfamethoxazole

  Minor (3)sulfamethoxazole will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
  
  hydrochlorothiazide increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
  
  hydrochlorothiazide, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.

• sulfasalazine

  Monitor Closely (3)metoprolol and sulfasalazine both increase serum potassium. Use Caution/Monitor.
  
  sulfasalazine decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.
  
  sulfasalazine increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)hydrochlorothiazide will increase the level or effect of sulfasalazine by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• sulfisoxazole

  Minor (1)hydrochlorothiazide increases levels of sulfisoxazole by unspecified interaction mechanism. Minor/Significance Unknown.

• sulindac

  Monitor Closely (3)metoprolol and sulindac both increase serum potassium. Use Caution/Monitor.
  
  sulindac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  sulindac decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.Minor (1)hydrochlorothiazide will increase the level or effect of sulindac by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• tadalafil

  Monitor Closely (2)tadalafil increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
  
  tadalafil increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• telmisartan

  Monitor Closely (3)telmisartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  telmisartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol, telmisartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

• temocillin

  Monitor Closely (1)temocillin, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• terazosin

  Monitor Closely (1)terazosin and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

• terbinafine

  Monitor Closely (1)terbinafine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.

• terbutaline

  Monitor Closely (4)metoprolol decreases effects of terbutaline by pharmacodynamic antagonism. Use Caution/Monitor.
  
  metoprolol increases and terbutaline decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol increases effects of terbutaline by pharmacodynamic synergism. Use Caution/Monitor.
  
  terbutaline and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (2)hydrochlorothiazide, terbutaline. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive hypokalemic effects.
  
  terbutaline, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• theophylline

  Monitor Closely (1)metoprolol, theophylline. Other (see comment). Use Caution/Monitor. Comment: Beta blockers (esp. non selective) antagonize theophylline effects, while at the same time increasing theophylline levels and toxicity (mechanism: decreased theophylline metabolism). Smoking increases risk of interaction.

• thioridazine

  Monitor Closely (1)thioridazine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)metoprolol, thioridazine. Either increases levels of the other by decreasing metabolism. Contraindicated. Not all beta blockers share this interaction (e.g., atenolol, nadolol, sotalol do not interact).

• thiothixene

  Serious - Use Alternative (1)metoprolol, thiothixene. Either increases levels of the other by decreasing metabolism. Contraindicated. Not all beta blockers share this interaction (e.g., atenolol, nadolol, sotalol do not interact).

• ticarcillin

  Monitor Closely (1)ticarcillin, hydrochlorothiazide. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• timolol

  Monitor Closely (2)metoprolol and timolol both increase serum potassium. Use Caution/Monitor.
  
  timolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)metoprolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

• tipranavir

  Monitor Closely (1)tipranavir will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• tizanidine

  Minor (2)tizanidine increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypotension.
  
  tizanidine increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypotension.

• tolazamide

  Minor (1)hydrochlorothiazide decreases effects of tolazamide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• tolbutamide

  Minor (1)hydrochlorothiazide decreases effects of tolbutamide by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• tolfenamic acid

  Monitor Closely (3)tolfenamic acid increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and tolfenamic acid both increase serum potassium. Use Caution/Monitor.
  
  tolfenamic acid decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.Minor (1)hydrochlorothiazide will increase the level or effect of tolfenamic acid by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• tolmetin

  Monitor Closely (3)tolmetin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and tolmetin both increase serum potassium. Use Caution/Monitor.
  
  tolmetin decreases effects of metoprolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.Minor (1)hydrochlorothiazide will increase the level or effect of tolmetin by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• tolvaptan

  Monitor Closely (2)tolvaptan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metoprolol and tolvaptan both increase serum potassium. Use Caution/Monitor.

• toremifene

  Monitor Closely (1)hydrochlorothiazide, toremifene. Other (see comment). Use Caution/Monitor. Comment: Thiazide diuretics decrease renal calcium excretion and may increase risk of hypercalcemia in patients taking toremifene.

• torsemide

  Monitor Closely (2)torsemide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  metoprolol increases and torsemide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• treprostinil

  Minor (2)treprostinil increases effects of metoprolol by pharmacodynamic synergism. Minor/Significance Unknown.
  
  treprostinil increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.

• tretinoin

  Serious - Use Alternative (1)hydrochlorothiazide, tretinoin. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.

• tretinoin topical

  Serious - Use Alternative (1)hydrochlorothiazide, tretinoin topical. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.

• triamcinolone acetonide injectable suspension

  Minor (1)triamcinolone acetonide injectable suspension, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypokalemia, especially with strong glucocorticoid activity.

• triamterene

  Monitor Closely (2)metoprolol and triamterene both increase serum potassium. Modify Therapy/Monitor Closely.
  
  triamterene increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.Minor (1)hydrochlorothiazide will increase the level or effect of triamterene by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• trientine

  Monitor Closely (1)hydrochlorothiazide decreases levels of trientine by increasing renal clearance. Use Caution/Monitor.

• trilostane

  Minor (1)trilostane, hydrochlorothiazide. Other (see comment). Minor/Significance Unknown. Comment: Trilostane reduces K+ loss while maintaining the natriuretic effect. Mechanism: inhibition of mineralocorticoid steroid synthesis.

• trimethoprim

  Minor (2)hydrochlorothiazide will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
  
  hydrochlorothiazide, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.

• umeclidinium bromide/vilanterol inhaled

  Monitor Closely (1)umeclidinium bromide/vilanterol inhaled and hydrochlorothiazide both decrease serum potassium. Modify Therapy/Monitor Closely. Electrocardiographic changes and/or hypokalemia associated with non?potassium-sparing diuretics may worsen with concomitant beta-agonists, particularly if recommended dose is exceeded

• valganciclovir

  Minor (1)hydrochlorothiazide will increase the level or effect of valganciclovir by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• valsartan

  Monitor Closely (3)metoprolol, valsartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.
  
  valsartan and metoprolol both increase serum potassium. Use Caution/Monitor.
  
  valsartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• venlafaxine

  Monitor Closely (1)venlafaxine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• verapamil

  Monitor Closely (1)metoprolol and verapamil both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.Serious - Use Alternative (1)verapamil, metoprolol. Either increases toxicity of the other by unspecified interaction mechanism. Avoid or Use Alternate Drug. Can increase risk of bradycardia.Minor (1)hydrochlorothiazide will increase the level or effect of verapamil by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• verteporfin

  Minor (1)hydrochlorothiazide, verteporfin. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Increased phototoxicity.

• vilanterol/fluticasone furoate inhaled

  Monitor Closely (1)vilanterol/fluticasone furoate inhaled and hydrochlorothiazide both decrease serum potassium. Modify Therapy/Monitor Closely. Beta-agonists may acutely worsen ECG changes and/or hypokalemia resulting from non-potassium-sparing diuretics

• vildagliptin

  Minor (1)hydrochlorothiazide decreases effects of vildagliptin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

• vitamin D

  Monitor Closely (1)hydrochlorothiazide increases effects of vitamin D by Other (see comment). Use Caution/Monitor. Comment: Combination may increase hypercalcemic effect of vitamin D analogs. Use with caution.

• willow bark

  Minor (1)hydrochlorothiazide will increase the level or effect of willow bark by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• xipamide

  Monitor Closely (2)xipamide increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor.
  
  xipamide increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor.

• yohimbe

  Minor (1)metoprolol decreases toxicity of yohimbe by pharmacodynamic antagonism. Minor/Significance Unknown.