hydralazine/hydrochlorothiazide (Rx)

Hypertension

Not for initial therapy

Usual dose: 25 mg/25 mg PO q12hr

Maximum: 100 mg/50 mg PO q12hr

Dosage strength determined by individual titration

Renal Impairment

Use caution in dosing/titrating patients with renal dysfunction

Cumulative effects of thiazides may develop with impaired renal function; dose adjustment may be necessary; azotemia may be precipitated

Hepatic Impairment

Not studied

Administration

Dosage adjustment may be required in geriatrics

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

<18 years: Safety/efficacy not established

Contraindicated (0)

Serious - Use Alternative (13)

• 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.

• carbamazepine

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

• 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.

• dofetilide

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

• isocarboxazid

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

• lofexidine

  lofexidine, hydralazine. 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, 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.

• lonafarnib

  hydralazine will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of lonafarnib (a sensitive CYP3A substrate) with weak CYP3A inhibitors is unavoidable, reduce to, or continue lonafarnib at starting dose. Closely monitor for arrhythmias and events (eg, syncope, heart palpitations) since lonafarnib effect on QT interval is unknown.

• 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.

• pexidartinib

  hydralazine and pexidartinib both increase Other (see comment). Avoid or Use Alternate Drug. Pexidartinib can cause hepatotoxicity. Avoid coadministration of pexidartinib with other products know to cause hepatoxicity.

• pretomanid

  hydralazine, pretomanid. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Pretomanid regimen associated with hepatotoxicity. Avoid alcohol and hepatotoxic agents, including herbal supplements and drugs other than bedaquiline and linezolid.

• squill

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

Monitor Closely (221)

• acebutolol

  acebutolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of acebutolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• aceclofenac

  aceclofenac decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  aceclofenac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• acemetacin

  acemetacin decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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.

• aldesleukin

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

• albuterol

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

• aldesleukin

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

• amifostine

  amifostine, hydralazine. 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

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

• aspirin

  aspirin decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• amiodarone

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

• amoxicillin

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

• arformoterol

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

• aspirin

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

• 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 hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• aspirin/citric acid/sodium bicarbonate

  aspirin/citric acid/sodium bicarbonate decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  aspirin/citric acid/sodium bicarbonate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• atenolol

  atenolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of atenolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• atogepant

  hydralazine will increase the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• avanafil

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

• avanafil

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

• axitinib

  hydralazine increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• beclomethasone, inhaled

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

• 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.

• benzphetamine

  hydralazine, benzphetamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• betaxolol

  betaxolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of betaxolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• bisoprolol

  bisoprolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of bisoprolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• bretylium

  hydralazine, 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

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

• carbidopa

  carbidopa increases effects of hydralazine 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.

• 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.

• 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.

• candesartan

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

• 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

  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.

• carvedilol

  carvedilol increases effects of hydralazine by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  hydralazine increases effects of carvedilol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  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 decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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.
  
  hydrochlorothiazide decreases levels of celiprolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.

• chlorothiazide

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

• chlorthalidone

  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

  choline magnesium trisalicylate decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• citalopram

  hydrochlorothiazide, citalopram. pharmacodynamic synergism. Use Caution/Monitor. Possible additive hyponatremia.

• cornsilk

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

• corticotropin

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

• cyclopenthiazide

  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.

• deflazacort

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

• dexfenfluramine

  hydralazine, dexfenfluramine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• dexmethylphenidate

  hydralazine, dexmethylphenidate. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• dextroamphetamine

  hydralazine, dextroamphetamine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• 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.
  
  diclofenac decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• dicloxacillin

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

• diethylpropion

  hydralazine, diethylpropion. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• diflunisal

  diflunisal decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  diflunisal increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• digoxin

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

• dobutamine

  hydralazine, dobutamine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• dobutamine

  dobutamine and hydrochlorothiazide both decrease serum potassium. 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.

• dopamine

  hydralazine, dopamine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• dopexamine

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

• drospirenone

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

• 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

  hydralazine, ephedrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.
  
  ephedrine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• epinephrine

  hydralazine, epinephrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.
  
  epinephrine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• epinephrine racemic

  epinephrine racemic and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• epoprostenol

  epoprostenol, hydralazine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.

• eprosartan

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

• esmolol

  hydralazine increases effects of esmolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  esmolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• ethacrynic acid

  ethacrynic acid and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• etodolac

  etodolac decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• etodolac

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

• 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.

• fenfluramine

  hydralazine, fenfluramine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• fenoldopam

  fenoldopam, hydralazine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.

• fenoprofen

  fenoprofen decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  fenoprofen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. 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).

• finerenone

  hydralazine will increase the level or effect of finerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor serum potassium during initiation and dosage adjustment of either finererone or weak CYP3A4 inhibitors. Adjust finererone dosage as needed.

• 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).

• flibanserin

  hydralazine will increase the level or effect of flibanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Increased flibanserin adverse effects may occur if coadministered with multiple weak CYP3A4 inhibitors.

• flurbiprofen

  flurbiprofen decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  flurbiprofen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• formoterol

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

• ibuprofen

  ibuprofen decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• furosemide

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

• gentamicin

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

• ibuprofen

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

• ibuprofen IV

  ibuprofen IV decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  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.

• iloprost

  hydralazine, iloprost. Either increases effects of the other by pharmacodynamic synergism. 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.

• indapamide

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

• indomethacin

  indomethacin decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  indomethacin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• insulin degludec

  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.

• isavuconazonium sulfate

  hydralazine will increase the level or effect of isavuconazonium sulfate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• insulin degludec/insulin aspart

  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

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

• isocarboxazid

  hydralazine, isocarboxazid. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• isoproterenol

  hydralazine, isoproterenol. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.
  
  isoproterenol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• ivacaftor

  hydralazine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• 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.

• ketoprofen

  ketoprofen decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  ketoprofen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• ketorolac

  ketorolac decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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 hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  ketorolac intranasal increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor. .

• labetalol

  hydralazine increases effects of labetalol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  labetalol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• lemborexant

  hydralazine will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Lower nightly dose of lemborexant recommended if coadministered with weak CYP3A4 inhibitors. See drug monograph for specific dosage modification.

• levalbuterol

  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 hydralazine 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.

• linezolid

  hydralazine, linezolid. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• 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.

• lisdexamfetamine

  hydralazine, lisdexamfetamine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• lithium

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

• lomitapide

  hydralazine increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lomitapide dose should not exceed 30 mg/day.

• lornoxicam

  lornoxicam increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  lornoxicam decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• losartan

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

• meclofenamate

  meclofenamate decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• lurasidone

  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).

• meclofenamate

  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.
  
  mefenamic acid decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• meloxicam

  meloxicam decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  meloxicam increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• metaproterenol

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

• methamphetamine

  hydralazine, methamphetamine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• methoxsalen

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

• methylenedioxymethamphetamine

  hydralazine, methylenedioxymethamphetamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• methylphenidate

  hydralazine, methylphenidate. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• 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

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

• midazolam intranasal

  hydralazine will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of mild CYP3A4 inhibitors with midazolam intranasal may cause higher midazolam systemic exposure, which may prolong sedation.

• mometasone inhaled

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

• midodrine

  hydralazine, midodrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• minoxidil

  hydralazine, minoxidil. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.

• mipomersen

  mipomersen, hydralazine. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Both drugs have potential to increase hepatic enzymes; monitor LFTs.

• 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 hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• nadolol

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

  naproxen decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• naproxen

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

• nebivolol

  hydralazine increases effects of nebivolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  nebivolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• nitroglycerin rectal

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

• norepinephrine

  norepinephrine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  hydralazine, norepinephrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• 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. .

• oxaprozin

  oxaprozin decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• 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

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

• parecoxib

  parecoxib decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  parecoxib increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• penbutolol

  hydralazine increases effects of penbutolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  penbutolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• penicillin G aqueous

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

• phendimetrazine

  hydralazine, phendimetrazine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• phenelzine

  hydralazine, phenelzine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• phentermine

  hydralazine, phentermine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• phenylephrine

  hydralazine, phenylephrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• phenylephrine PO

  hydralazine, phenylephrine PO. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• pindolol

  pindolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of pindolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• pirbuterol

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

• piroxicam

  piroxicam decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• piroxicam

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

• pivmecillinam

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

• 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.

• potassium chloride

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

• potassium citrate

  potassium citrate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. 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.

• procainamide

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

• procarbazine

  hydralazine, procarbazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• propranolol

  hydralazine increases effects of propranolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  propranolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• propylhexedrine

  hydralazine, propylhexedrine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• quinidine

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

• pseudoephedrine

  hydralazine, pseudoephedrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• sacubitril/valsartan

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

• salicylates (non-asa)

  salicylates (non-asa) decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  salicylates (non-asa) increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• salmeterol

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

• salsalate

  salsalate decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• salsalate

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

• serdexmethylphenidate/dexmethylphenidate

  hydralazine, serdexmethylphenidate/dexmethylphenidate. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.
  
  hydralazine, serdexmethylphenidate/dexmethylphenidate. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• shark cartilage

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

• 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 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.

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

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

• sotalol

  sotalol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of sotalol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• spironolactone

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

• sulfasalazine

  sulfasalazine decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• succinylcholine

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

• sulfasalazine

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

• sulindac

  sulindac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  sulindac decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• tadalafil

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

• tazemetostat

  hydralazine will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• telmisartan

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

• temocillin

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

• terbutaline

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

• ticarcillin

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

• timolol

  timolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of timolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• tinidazole

  hydralazine will increase the level or effect of tinidazole by affecting hepatic/intestinal enzyme CYP3A4 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

  tolfenamic acid decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• tolmetin

  tolmetin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  tolmetin decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• tolvaptan

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

• tranylcypromine

  hydralazine, tranylcypromine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• 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

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

• treprostinil

  hydralazine, treprostinil. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.

• triamterene

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

• trientine

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

• 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.

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

• xylometazoline

  hydralazine, xylometazoline. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• yohimbine

  hydralazine, yohimbine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

Minor (159)

• 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.

• agrimony

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

• albuterol

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

• brimonidine

  brimonidine increases effects of hydralazine by pharmacodynamic synergism. 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.

• budesonide

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

• 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.

• celiprolol

  hydralazine increases effects of celiprolol by pharmacodynamic synergism. 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.

• 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 hydralazine 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.

• diazoxide

  diazoxide, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperglycemia.
  
  diazoxide, hydralazine. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive hypotensive effects.

• diclofenac

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

• forskolin

  forskolin increases effects of hydralazine by pharmacodynamic synergism. 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.

• 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.

• 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.

• 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 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.

• 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.

• 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.

• 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 hydralazine by pharmacodynamic synergism. Minor/Significance Unknown. Maitake mushroom has anti-tumor effects (animal/in vitro research).

• 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.

• 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.

• noni juice

  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 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.

• parecoxib

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

• 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.

• 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.

• pyridoxine

  hydralazine decreases levels of pyridoxine by unspecified interaction mechanism. Minor/Significance Unknown.

• pyridoxine (Antidote)

  hydralazine decreases levels of pyridoxine (Antidote) by unspecified interaction mechanism. Minor/Significance Unknown.

• 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 hydralazine 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.

• ruxolitinib

  hydralazine will increase the level or effect of ruxolitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• 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.

• ruxolitinib topical

  hydralazine will increase the level or effect of ruxolitinib topical by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

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

• tizanidine

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

• 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 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.

• 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 hydralazine by pharmacodynamic synergism. Minor/Significance Unknown.
  
  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.

• 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 increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of acebutolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• aceclofenac

  Monitor Closely (2)aceclofenac decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  aceclofenac 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 aceclofenac by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• acemetacin

  Monitor Closely (2)acemetacin decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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.

• agrimony

  Minor (2)agrimony increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.
  
  agrimony increases effects of hydralazine 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 (1)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 hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
  
  aldesleukin increases effects of hydralazine by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• amifostine

  Monitor Closely (2)amifostine, hydralazine. 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 (1)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 (1)amiodarone will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• 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.

• arformoterol

  Monitor Closely (1)arformoterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)arformoterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• aspirin

  Monitor Closely (2)aspirin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  aspirin decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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 (2)aspirin rectal increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor. .
  
  aspirin rectal decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.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 (2)aspirin/citric acid/sodium bicarbonate decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  aspirin/citric acid/sodium bicarbonate 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 aspirin/citric acid/sodium bicarbonate by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• atenolol

  Monitor Closely (2)atenolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of atenolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• atogepant

  Monitor Closely (1)hydralazine will increase the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• avanafil

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

• axitinib

  Monitor Closely (1)hydralazine increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• 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 (1)bendroflumethiazide and hydrochlorothiazide both decrease serum potassium. 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.

• benzphetamine

  Monitor Closely (1)hydralazine, benzphetamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• betaxolol

  Monitor Closely (2)betaxolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of betaxolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• birch

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

• bisoprolol

  Monitor Closely (2)bisoprolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of bisoprolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• bitter melon

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

• bretylium

  Monitor Closely (2)hydralazine, 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 hydralazine by pharmacodynamic synergism. Minor/Significance Unknown.
  
  brimonidine increases effects of hydrochlorothiazide 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 (1)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.

• 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

  Minor (1)hydrochlorothiazide increases levels of calcium acetate by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• calcium carbonate

  Minor (1)hydrochlorothiazide increases levels of calcium carbonate by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• calcium chloride

  Minor (1)hydrochlorothiazide increases levels of calcium chloride by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• calcium citrate

  Minor (1)hydrochlorothiazide increases levels of calcium citrate by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• calcium gluconate

  Minor (1)hydrochlorothiazide increases levels of calcium gluconate by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis, hypercalcemia.

• candesartan

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

• 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 (1)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 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 hydralazine 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 (3)carvedilol increases effects of hydralazine by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  hydralazine increases effects of carvedilol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  carvedilol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• 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 (2)celecoxib increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  celecoxib decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.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 (2)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.Minor (1)hydralazine increases effects of celiprolol by pharmacodynamic synergism. Minor/Significance Unknown.

• cephalexin

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

• chlorothiazide

  Monitor Closely (1)chlorothiazide and hydrochlorothiazide both decrease serum potassium. 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.

• 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 (1)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 (1)choline magnesium trisalicylate decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

• citalopram

  Monitor Closely (1)hydrochlorothiazide, citalopram. pharmacodynamic synergism. Use Caution/Monitor. Possible additive hyponatremia.

• 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 hydralazine 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 (1)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.

• 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.

• dexamethasone

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

• dexfenfluramine

  Monitor Closely (1)hydralazine, dexfenfluramine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• dexmethylphenidate

  Monitor Closely (1)hydralazine, dexmethylphenidate. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• dextroamphetamine

  Monitor Closely (1)hydralazine, dextroamphetamine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• diazoxide

  Monitor Closely (1)hydrochlorothiazide increases toxicity of diazoxide by unspecified interaction mechanism. Use Caution/Monitor. May enhance hyperglycemic effects of diazoxide.Minor (2)diazoxide, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperglycemia.
  
  diazoxide, hydralazine. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive hypotensive effects.

• dichlorphenamide

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

• diclofenac

  Monitor Closely (2)diclofenac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  diclofenac decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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.

• diethylpropion

  Monitor Closely (1)hydralazine, diethylpropion. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• diflunisal

  Monitor Closely (2)diflunisal decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  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 (3)digoxin will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
  
  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.

• dobutamine

  Monitor Closely (2)dobutamine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  hydralazine, dobutamine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.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.

• dopamine

  Monitor Closely (1)hydralazine, dopamine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• dopexamine

  Monitor Closely (1)dopexamine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)dopexamine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• drospirenone

  Monitor Closely (1)drospirenone increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.

• 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 (2)hydralazine, ephedrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.
  
  ephedrine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)ephedrine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• epinephrine

  Monitor Closely (2)hydralazine, epinephrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.
  
  epinephrine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)epinephrine, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• epinephrine racemic

  Monitor Closely (1)epinephrine racemic and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)epinephrine racemic, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• epoprostenol

  Monitor Closely (1)epoprostenol, hydralazine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.Minor (1)epoprostenol increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown. Additive hypotensive effects.

• eprosartan

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

• esmolol

  Monitor Closely (2)hydralazine increases effects of esmolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  esmolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• ethacrynic acid

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

• etodolac

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

• 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.

• fenbufen

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

• fenfluramine

  Monitor Closely (1)hydralazine, fenfluramine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• fenoldopam

  Monitor Closely (1)fenoldopam, hydralazine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.

• fenoprofen

  Monitor Closely (2)fenoprofen decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  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).

• finerenone

  Monitor Closely (1)hydralazine will increase the level or effect of finerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor serum potassium during initiation and dosage adjustment of either finererone or weak CYP3A4 inhibitors. Adjust finererone dosage as needed.

• flibanserin

  Monitor Closely (1)hydralazine will increase the level or effect of flibanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Increased flibanserin adverse effects may occur if coadministered with multiple weak CYP3A4 inhibitors.

• fludrocortisone

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

• flurbiprofen

  Monitor Closely (2)flurbiprofen decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  flurbiprofen 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 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 (1)formoterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)formoterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• forskolin

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

• furosemide

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

• 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.

• 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.

• hydrocortisone

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

• ibuprofen

  Monitor Closely (2)ibuprofen increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  ibuprofen decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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 (3)ibuprofen IV decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  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.

• iloprost

  Monitor Closely (1)hydralazine, iloprost. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.

• indacaterol, inhaled

  Monitor Closely (2)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.

• indapamide

  Monitor Closely (1)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 (2)indomethacin decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  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 (1)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 (1)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 (1)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 (1)irbesartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• isavuconazonium sulfate

  Monitor Closely (1)hydralazine will increase the level or effect of isavuconazonium sulfate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• isocarboxazid

  Monitor Closely (1)hydralazine, isocarboxazid. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.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 (2)isoproterenol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  hydralazine, isoproterenol. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.Minor (1)isoproterenol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• ivacaftor

  Monitor Closely (1)hydralazine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor when coadministered with weak CYP3A4 inhibitors .

• 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.

• ketoprofen

  Monitor Closely (2)ketoprofen decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  ketoprofen 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 ketoprofen by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• ketorolac

  Monitor Closely (2)ketorolac decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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 (2)ketorolac intranasal decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  ketorolac intranasal 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 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)hydralazine increases effects of labetalol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  labetalol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• lemborexant

  Monitor Closely (1)hydralazine will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Lower nightly dose of lemborexant recommended if coadministered with weak CYP3A4 inhibitors. See drug monograph for specific dosage modification.

• levalbuterol

  Monitor Closely (1)levalbuterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)levalbuterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• 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 hydralazine 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.

• linezolid

  Monitor Closely (1)hydralazine, linezolid. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• 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.

• lisdexamfetamine

  Monitor Closely (1)hydralazine, lisdexamfetamine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• 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, hydralazine. 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.

• lomitapide

  Monitor Closely (1)hydralazine increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lomitapide dose should not exceed 30 mg/day.

• lonafarnib

  Serious - Use Alternative (1)hydralazine will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of lonafarnib (a sensitive CYP3A substrate) with weak CYP3A inhibitors is unavoidable, reduce to, or continue lonafarnib at starting dose. Closely monitor for arrhythmias and events (eg, syncope, heart palpitations) since lonafarnib effect on QT interval is unknown.

• lornoxicam

  Monitor Closely (2)lornoxicam increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  lornoxicam decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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 (1)losartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• lurasidone

  Monitor Closely (1)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 hydralazine by pharmacodynamic synergism. Minor/Significance Unknown. Maitake mushroom has anti-tumor effects (animal/in vitro research).

• meclofenamate

  Monitor Closely (2)meclofenamate decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  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 (2)mefenamic acid increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  mefenamic acid decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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.

• meloxicam

  Monitor Closely (2)meloxicam decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  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 (1)metaproterenol and hydrochlorothiazide both decrease serum potassium. 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.

• methamphetamine

  Monitor Closely (1)hydralazine, methamphetamine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• 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.

• 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.

• methylenedioxymethamphetamine

  Monitor Closely (1)hydralazine, methylenedioxymethamphetamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• methylphenidate

  Monitor Closely (1)hydralazine, methylphenidate. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• 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.

• metolazone

  Monitor Closely (1)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 (3)hydralazine increases effects of metoprolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  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.

• midazolam intranasal

  Monitor Closely (1)hydralazine will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of mild CYP3A4 inhibitors with midazolam intranasal may cause higher midazolam systemic exposure, which may prolong sedation.

• midodrine

  Monitor Closely (1)hydralazine, midodrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.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

  Monitor Closely (1)hydralazine, minoxidil. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.Minor (1)hydrochlorothiazide increases effects of minoxidil by pharmacodynamic synergism. Minor/Significance Unknown.

• mipomersen

  Monitor Closely (1)mipomersen, hydralazine. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Both drugs have potential to increase hepatic enzymes; monitor LFTs.

• 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.

• 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 (2)nabumetone increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  nabumetone decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.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)hydralazine increases effects of nadolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  nadolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• nafcillin

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

• naproxen

  Monitor Closely (2)naproxen decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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)hydralazine increases effects of nebivolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  nebivolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• nitroglycerin rectal

  Monitor Closely (2)nitroglycerin rectal, hydralazine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Observe for possible additive hypotensive effects during concomitant use. .
  
  nitroglycerin rectal, hydrochlorothiazide. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Observe for possible additive hypotensive effects during concomitant use. .

• noni juice

  Minor (1)noni juice increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Minor/Significance Unknown.

• norepinephrine

  Monitor Closely (2)norepinephrine and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.
  
  hydralazine, norepinephrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.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 (1)octacosanol increases effects of hydrochlorothiazide 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 (1)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 (2)oxaprozin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  oxaprozin decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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.

• parecoxib

  Monitor Closely (2)parecoxib decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  parecoxib 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 parecoxib by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• penbutolol

  Monitor Closely (2)hydralazine increases effects of penbutolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
  
  penbutolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• 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.

• pexidartinib

  Serious - Use Alternative (1)hydralazine and pexidartinib both increase Other (see comment). Avoid or Use Alternate Drug. Pexidartinib can cause hepatotoxicity. Avoid coadministration of pexidartinib with other products know to cause hepatoxicity.

• phendimetrazine

  Monitor Closely (1)hydralazine, phendimetrazine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• phenelzine

  Monitor Closely (1)hydralazine, phenelzine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• phentermine

  Monitor Closely (1)hydralazine, phentermine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• phenylephrine

  Monitor Closely (1)hydralazine, phenylephrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• phenylephrine PO

  Monitor Closely (1)hydralazine, phenylephrine PO. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• pindolol

  Monitor Closely (2)pindolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of pindolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• 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 (1)pirbuterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)pirbuterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• piroxicam

  Monitor Closely (2)piroxicam decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  piroxicam 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 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.

• porfimer

  Monitor Closely (1)hydrochlorothiazide, porfimer. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Enhanced photosensitivity.

• potassium acid phosphate

  Monitor Closely (1)potassium acid phosphate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.

• potassium chloride

  Monitor Closely (1)potassium chloride increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.

• potassium citrate

  Monitor Closely (1)potassium citrate increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. 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.

• pretomanid

  Serious - Use Alternative (1)hydralazine, pretomanid. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Pretomanid regimen associated with hepatotoxicity. Avoid alcohol and hepatotoxic agents, including herbal supplements and drugs other than bedaquiline and linezolid.

• 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.

• procarbazine

  Monitor Closely (1)hydralazine, procarbazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• propranolol

  Monitor Closely (2)propranolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of propranolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• propylhexedrine

  Monitor Closely (1)hydralazine, propylhexedrine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• pseudoephedrine

  Monitor Closely (1)hydralazine, pseudoephedrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• pyridoxine

  Minor (1)hydralazine decreases levels of pyridoxine by unspecified interaction mechanism. Minor/Significance Unknown.

• pyridoxine (Antidote)

  Minor (1)hydralazine decreases levels of pyridoxine (Antidote) by unspecified interaction mechanism. Minor/Significance Unknown.

• 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.

• quinine

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

• reishi

  Minor (2)reishi increases effects of hydrochlorothiazide by pharmacodynamic synergism. Minor/Significance Unknown.
  
  reishi increases effects of hydralazine 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.

• 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.

• ruxolitinib

  Minor (1)hydralazine will increase the level or effect of ruxolitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• ruxolitinib topical

  Minor (1)hydralazine will increase the level or effect of ruxolitinib topical by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• sacubitril/valsartan

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

• salicylates (non-asa)

  Monitor Closely (2)salicylates (non-asa) decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  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 (1)salmeterol and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (1)salmeterol, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.

• salsalate

  Monitor Closely (2)salsalate decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
  
  salsalate 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 salsalate by acidic (anionic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• saxagliptin

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

• serdexmethylphenidate/dexmethylphenidate

  Monitor Closely (2)hydralazine, serdexmethylphenidate/dexmethylphenidate. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.
  
  hydralazine, serdexmethylphenidate/dexmethylphenidate. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

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

• sitagliptin

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

• 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 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.

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

  Monitor Closely (1)hydrochlorothiazide and sodium sulfate/potassium sulfate/magnesium sulfate/polyethylene glycol both decrease serum potassium. Modify Therapy/Monitor Closely.

• sotalol

  Monitor Closely (2)sotalol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of sotalol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• spironolactone

  Monitor Closely (1)spironolactone increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. 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 (1)succinylcholine increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. 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 (2)sulfasalazine decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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 (2)sulindac increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  sulindac decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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 hydralazine by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
  
  tadalafil increases effects of hydrochlorothiazide by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• tazemetostat

  Monitor Closely (1)hydralazine will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• telmisartan

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

• temocillin

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

• terbutaline

  Monitor Closely (1)terbutaline and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.Minor (2)terbutaline, hydrochlorothiazide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Hypokalemia.
  
  hydrochlorothiazide, terbutaline. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive hypokalemic effects.

• ticarcillin

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

• timolol

  Monitor Closely (2)timolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  hydralazine increases effects of timolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

• tinidazole

  Monitor Closely (1)hydralazine will increase the level or effect of tinidazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tizanidine

  Minor (2)tizanidine increases effects of hydralazine 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 (2)tolfenamic acid increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  tolfenamic acid decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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 (2)tolmetin increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  tolmetin decreases effects of hydralazine by pharmacodynamic antagonism. Use Caution/Monitor. 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 (1)tolvaptan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. 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 (1)torsemide and hydrochlorothiazide both decrease serum potassium. Use Caution/Monitor.

• tranylcypromine

  Monitor Closely (1)hydralazine, tranylcypromine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

• treprostinil

  Monitor Closely (1)hydralazine, treprostinil. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.Minor (2)treprostinil increases effects of hydralazine 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 (1)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 (1)valsartan increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• verapamil

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

• xylometazoline

  Monitor Closely (1)hydralazine, xylometazoline. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hypertension.

• yohimbine

  Monitor Closely (1)hydralazine, yohimbine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.