cimetidine (Rx)

Benign Gastric Ulcer

800 mg PO qHS OR

400 mg PO q12hr OR

300 mg PO q6hr

Duodenal Ulcer

800 mg PO qHS OR

400 mg PO q12hr OR

300 mg PO q6hr

Erosive Gastroesophageal Reflux Disease

800 mg PO q12hr OR

400 mg PO q6hr

Heartburn

Over the counter only

To relieve symptoms: 200 mg PO up to q12hr

To prevent symptoms: 200 mg PO with glass of water right before or any time up to 30 minutes before eating food or drinking beverages that cause heartburn

Pathological Hypersecretory Conditions

300 mg PO q6hr with meals and HS

Renal Impairment

CrCl<30 mL/min

300 mg IV/IO q12hr

Prevention of upper GI bleeding: 25 mg/hour continuous IV infusion

Other Indications & Uses

PUD (treatment, maintenance), gastric ulcer treatment, GI bleeding prevention in critically ill patients, hypersecretory conditions (e.g., Zollinger-Ellison)

Duodenal Ulcer (Off-label)

<16 years: Use only if benefit outweighs risks

20-40 mg/kg/day IV/PO divided q6hr  

Neonates (<28 days old): 5-20 mg/kg/day IV/PO divided q8-12hr

Infants: 10-20 mg/kg/day IV/PO divided q6-12hr

Not drug of choice in elderly because of increased potential for confusion and drug interactions

Benign Gastric Ulcer

800 mg PO qHS OR

400 mg PO q12hr OR

300 mg PO q6hr

Duodenal Ulcer

800 mg PO qHS OR

400 mg PO q12hr OR

300 mg PO q6hr

Erosive Gastroesophageal Reflux Disease

800 mg PO q12hr OR

400 mg PO q6hr

Contraindicated (4)

• dofetilide

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

• eliglustat

  cimetidine increases levels of eliglustat by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated. If coadministered with strong or moderate CYP2D6 inhibitors, reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive and intermediate metabolizers; eliglustat is contraindiated if strong or moderate CYP2D6 inhibitors are given concomitantly with strong or moderate CYP3A inhibitors.

• lomitapide

  cimetidine increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Increases lomitapide levels several folds.

• pimozide

  cimetidine increases levels of pimozide by decreasing metabolism. Contraindicated. Risk of QT interval prolongation.

Serious - Use Alternative (142)

• alitretinoin

  cimetidine will increase the level or effect of alitretinoin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• alosetron

  cimetidine will increase the level or effect of alosetron by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug.

• alprazolam

  cimetidine will increase the level or effect of alprazolam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• amiodarone

  cimetidine will increase the level or effect of amiodarone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• aprepitant

  cimetidine will increase the level or effect of aprepitant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• aripiprazole

  cimetidine will increase the level or effect of aripiprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• artemether/lumefantrine

  cimetidine will increase the level or effect of artemether/lumefantrine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• atazanavir

  cimetidine will decrease the level or effect of atazanavir by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Atazanavir solubility decreases as pH increases. Substantially reduced plasma concentrations of atazanavir are expected if H2-receptor antagonists (H2RA) are coadministered. For treatment-naïve patients, take atazanavir simultaneously with the H2RA or at least 10 h afterwards. See dosage adjustment recommendations if coadministered in treatment-experienced patients.

• atorvastatin

  cimetidine will increase the level or effect of atorvastatin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• axitinib

  cimetidine increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with moderate CYP3A4 inhibitors, monitor closely and reduce dose if necessary .

• bazedoxifene/conjugated estrogens

  cimetidine will increase the level or effect of bazedoxifene/conjugated estrogens by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• belladonna and opium

  cimetidine increases effects of belladonna and opium by decreasing metabolism. Avoid or Use Alternate Drug.

• bosutinib

  cimetidine increases levels of bosutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• budesonide

  cimetidine will increase the level or effect of budesonide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• buprenorphine

  cimetidine increases effects of buprenorphine by decreasing metabolism. Avoid or Use Alternate Drug.

• buprenorphine buccal

  cimetidine increases effects of buprenorphine buccal by decreasing metabolism. Avoid or Use Alternate Drug.

• buspirone

  cimetidine will increase the level or effect of buspirone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• butorphanol

  cimetidine increases effects of butorphanol by decreasing metabolism. Avoid or Use Alternate Drug.

• chloroquine

  cimetidine increases levels of chloroquine by decreasing metabolism. Avoid or Use Alternate Drug.

• cilostazol

  cimetidine will increase the level or effect of cilostazol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• cinacalcet

  cimetidine will increase the level or effect of cinacalcet by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• clopidogrel

  cimetidine decreases effects of clopidogrel by affecting hepatic enzyme CYP2C19 metabolism. Avoid or Use Alternate Drug. Clopidogrel efficacy may be reduced by drugs that inhibit CYP2C19. Inhibition of platelet aggregation by clopidogrel is entirely due to an active metabolite. Clopidogrel is metabolized to this active metabolite in part by CYP2C19. .

• clozapine

  cimetidine will increase the level or effect of clozapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• conjugated estrogens

  cimetidine will increase the level or effect of conjugated estrogens by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• conjugated estrogens, vaginal

  cimetidine will increase the level or effect of conjugated estrogens, vaginal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• cyclosporine

  cimetidine will increase the level or effect of cyclosporine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• darifenacin

  cimetidine will increase the level or effect of darifenacin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• darolutamide

  darolutamide will increase the level or effect of cimetidine by Other (see comment). Avoid or Use Alternate Drug. Darolutamide is a BCRP inhibitor. Avoid coadministration with BCRP inhibitors. If use is unavoidable, closely monitor for adverse reactions and consider dose reduction of BCRP substrate drug (refer BCRP substrate prescribing information).

• darunavir

  cimetidine will increase the level or effect of darunavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• dasatinib

  cimetidine will increase the level or effect of dasatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  cimetidine will decrease the level or effect of dasatinib by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• dexamethasone

  cimetidine will increase the level or effect of dexamethasone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• diazepam

  cimetidine will increase the level or effect of diazepam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• difenoxin hcl

  cimetidine increases effects of difenoxin hcl by decreasing metabolism. Avoid or Use Alternate Drug.

• dihydroergotamine

  cimetidine will increase the level or effect of dihydroergotamine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• dihydroergotamine intranasal

  cimetidine will increase the level or effect of dihydroergotamine intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• diphenoxylate hcl

  cimetidine increases effects of diphenoxylate hcl by decreasing metabolism. Avoid or Use Alternate Drug.

• dofetilide

  cimetidine will increase the level or effect of dofetilide by basic (cationic) drug competition for renal tubular clearance. Avoid or Use Alternate Drug.

• dronedarone

  cimetidine will increase the level or effect of dronedarone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• duloxetine

  cimetidine will increase the level or effect of duloxetine by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug.

• eletriptan

  cimetidine will increase the level or effect of eletriptan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• eliglustat

  cimetidine increases levels of eliglustat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Moderate CYP3A4 inhibitors are not recommended with eliglustat poor or intermediate metabolizers; reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive metabolizers .

• erdafitinib

  erdafitinib will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ergotamine

  cimetidine will increase the level or effect of ergotamine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• erythromycin base

  cimetidine will increase the level or effect of erythromycin base by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• erythromycin ethylsuccinate

  cimetidine will increase the level or effect of erythromycin ethylsuccinate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• erythromycin lactobionate

  cimetidine will increase the level or effect of erythromycin lactobionate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• erythromycin stearate

  cimetidine will increase the level or effect of erythromycin stearate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• estradiol

  cimetidine will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• estrogens conjugated synthetic

  cimetidine will increase the level or effect of estrogens conjugated synthetic by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• estropipate

  cimetidine will increase the level or effect of estropipate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• etravirine

  cimetidine will increase the level or effect of etravirine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• everolimus

  cimetidine will increase the level or effect of everolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• fedratinib

  cimetidine will increase the level or effect of fedratinib by Other (see comment). Avoid or Use Alternate Drug. Avoid coadministration of fedratinib (a CYP3A4 and CYP2C19 substrate) with dual CYP3A4 and CYP2C19 inhibitor. Effect of coadministration of a dual CYP3A4 and CYP2C19 inhibitor with fedratinib has not been studied.

• felodipine

  cimetidine will increase the level or effect of felodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• fentanyl

  cimetidine will increase the level or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl intranasal

  cimetidine will increase the level or effect of fentanyl intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl transdermal

  cimetidine will increase the level or effect of fentanyl transdermal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl transmucosal

  cimetidine will increase the level or effect of fentanyl transmucosal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fesoterodine

  cimetidine will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• fludrocortisone

  cimetidine will increase the level or effect of fludrocortisone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• fluoxetine

  fluoxetine will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Avoid or Use Alternate Drug.

• fluvoxamine

  fluvoxamine will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Avoid or Use Alternate Drug.

• fosamprenavir

  cimetidine will increase the level or effect of fosamprenavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• hydrocortisone

  cimetidine will increase the level or effect of hydrocortisone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• hydromorphone

  cimetidine increases effects of hydromorphone by decreasing metabolism. Avoid or Use Alternate Drug.

• hydroxyprogesterone caproate

  cimetidine will increase the level or effect of hydroxyprogesterone caproate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• iloperidone

  cimetidine will increase the level or effect of iloperidone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• indinavir

  cimetidine will increase the level or effect of indinavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  cimetidine will decrease the level or effect of indinavir by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• infigratinib

  cimetidine will decrease the level or effect of infigratinib by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. If use with an acid-reducing agent cannot be avoided, administer infigratinib 2 hr before or 10 hr after administration of a H2-antagonist.

• irinotecan

  cimetidine will increase the level or effect of irinotecan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• irinotecan liposomal

  cimetidine will increase the level or effect of irinotecan liposomal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• ivabradine

  cimetidine will increase the level or effect of ivabradine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of ivabradine with moderate CYP3A4 inhibitors.

• ivacaftor

  ivacaftor increases levels of cimetidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• ixabepilone

  cimetidine will increase the level or effect of ixabepilone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• ketoconazole

  cimetidine will decrease the level or effect of ketoconazole by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• lasmiditan

  lasmiditan increases levels of cimetidine by Other (see comment). Avoid or Use Alternate Drug. Comment: Lasmiditan inhibits BCRP in vitro. Avoid coadministration of lasmiditan with BCRP substrates.

• levorphanol

  cimetidine increases effects of levorphanol by decreasing metabolism. Avoid or Use Alternate Drug.

• lonafarnib

  cimetidine 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.

• lopinavir

  cimetidine will increase the level or effect of lopinavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• loratadine

  cimetidine will increase the level or effect of loratadine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• lovastatin

  cimetidine will increase the level or effect of lovastatin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• lumefantrine

  cimetidine will increase the level or effect of lumefantrine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• maraviroc

  cimetidine will increase the level or effect of maraviroc by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• meperidine

  cimetidine increases effects of meperidine by decreasing metabolism. Avoid or Use Alternate Drug.

• mestranol

  cimetidine will increase the level or effect of mestranol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• methadone

  cimetidine will increase the level or effect of methadone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  cimetidine increases effects of methadone by decreasing metabolism. Avoid or Use Alternate Drug.

• midazolam

  cimetidine will increase the level or effect of midazolam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• morphine

  cimetidine increases effects of morphine by decreasing metabolism. Avoid or Use Alternate Drug.

• nalbuphine

  cimetidine increases effects of nalbuphine by decreasing metabolism. Avoid or Use Alternate Drug.

• nelfinavir

  cimetidine will increase the level or effect of nelfinavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• neratinib

  cimetidine will decrease the level or effect of neratinib by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• nicardipine

  cimetidine will increase the level or effect of nicardipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• nilotinib

  cimetidine will increase the level or effect of nilotinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• nimodipine

  cimetidine will increase the level or effect of nimodipine by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• nisoldipine

  cimetidine will increase the level or effect of nisoldipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  cimetidine will increase the level or effect of nisoldipine by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• olaparib

  cimetidine will increase the level or effect of olaparib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with moderate CYP3A inhibitors cannot be avoided, reduce olaparib dose to 200 mg (capsule) or 150 mg (tablet) PO BID. Do not substitute tablets with capsules.

• opium tincture

  cimetidine increases effects of opium tincture by decreasing metabolism. Avoid or Use Alternate Drug.

• oxycodone

  cimetidine increases effects of oxycodone by decreasing metabolism. Avoid or Use Alternate Drug.

• oxymorphone

  cimetidine increases effects of oxymorphone by decreasing metabolism. Avoid or Use Alternate Drug.

• papaveretum

  cimetidine increases effects of papaveretum by decreasing metabolism. Avoid or Use Alternate Drug.

• pazopanib

  cimetidine will decrease the level or effect of pazopanib by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Avoid coadministration of pazopanib with drugs that raise gastric pH; consider short-acting antacids in place of PPIs and H2 antagonists; separate antacid and pazopanib dosing by several hours

• pentazocine

  cimetidine increases effects of pentazocine by decreasing metabolism. Avoid or Use Alternate Drug.

• pexidartinib

  cimetidine will increase the level or effect of pexidartinib by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate pexidartinib by 2 hr before or 10 hr after taking an H2-antagonist.

• pirfenidone

  cimetidine will increase the level or effect of pirfenidone by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug. Avoid; coadministration of pirfenidone and moderate CYP1A2 inhibitors result in moderately increased exposure to pirfenidone; if unable to avoid, decrease dose of moderate CYP1A2 inhibitor

• ponatinib

  cimetidine decreases levels of ponatinib by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• prednisone

  cimetidine will increase the level or effect of prednisone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• procainamide

  cimetidine will increase the level or effect of procainamide by basic (cationic) drug competition for renal tubular clearance. Avoid or Use Alternate Drug.

• quetiapine

  cimetidine will increase the level or effect of quetiapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• quinidine

  cimetidine will increase the level or effect of quinidine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  quinidine will increase the level or effect of cimetidine by basic (cationic) drug competition for renal tubular clearance. Avoid or Use Alternate Drug.

• ranolazine

  cimetidine will increase the level or effect of ranolazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• repaglinide

  cimetidine will increase the level or effect of repaglinide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• risedronate

  cimetidine will increase the level or effect of risedronate by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Applies only to delayed release formulation; accelerates pH-sensitive dissolution of delayed release risedronate

• ritonavir

  cimetidine will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• romidepsin

  cimetidine will increase the level or effect of romidepsin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• saquinavir

  cimetidine will increase the level or effect of saquinavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• secretin

  cimetidine, secretin. Other (see comment). Avoid or Use Alternate Drug. Comment: Concomitant use of H2-receptor antagonists may cause a hyperresponse in gastrin secretion in response to stimulation testing with secretin, falsely suggesting gastrinoma. Discontinue H2-receptor antagonists at least 2 days before administering secretin to aid in the diagnosis of gastrinoma.

• silodosin

  cimetidine will increase the level or effect of silodosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• simvastatin

  cimetidine will increase the level or effect of simvastatin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• sirolimus

  cimetidine will increase the level or effect of sirolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• solifenacin

  cimetidine will increase the level or effect of solifenacin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• sotorasib

  cimetidine will decrease the level or effect of sotorasib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If use with an acid-reducing agent cannot be avoided, administer sotorasib 4 hr before or 10 hr after administration of a locally-acting antacid.
  
  sotorasib will decrease the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If use is unavoidable, refer to the prescribing information of the P-gp substrate for dosage modifications.

• sufentanil

  cimetidine increases effects of sufentanil by decreasing metabolism. Avoid or Use Alternate Drug.

• sunitinib

  cimetidine will increase the level or effect of sunitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• tacrolimus

  cimetidine will increase the level or effect of tacrolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• tafenoquine

  tafenoquine will increase the level or effect of cimetidine by Other (see comment). Avoid or Use Alternate Drug. Tafenoquine inhibits organic cation transporter-2 (OCT2) and multidrug and toxin extrusion (MATE) transporters in vitro. Avoid coadministration with OCT2 or MATE substrates. If coadministration cannot be avoided, monitor for substrate-related toxicities and consider dosage reduction if needed based on product labeling of the coadministered drug.

• tapentadol

  cimetidine increases effects of tapentadol by decreasing metabolism. Avoid or Use Alternate Drug.

• temsirolimus

  cimetidine will increase the level or effect of temsirolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• tepotinib

  tepotinib will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If concomitant use unavoidable, reduce the P-gp substrate dosage if recommended in its approved product labeling.

• theophylline

  cimetidine will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• thioridazine

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

• tipranavir

  cimetidine will increase the level or effect of tipranavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• tizanidine

  cimetidine will increase the level or effect of tizanidine by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug.

• tofacitinib

  cimetidine increases levels of tofacitinib by decreasing metabolism. Avoid or Use Alternate Drug. Reduce tofacitinib dose to 5 mg qDay when coadministered with 1 or more concomitant medications that result in both moderate CYP3A4 inhibition and potent CYP2C19 inhibition.

• tolterodine

  cimetidine will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• tolvaptan

  cimetidine will increase the level or effect of tolvaptan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• triamcinolone acetonide injectable suspension

  cimetidine will increase the level or effect of triamcinolone acetonide injectable suspension by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• triazolam

  cimetidine will increase the level or effect of triazolam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• trilaciclib

  trilaciclib will decrease the level or effect of cimetidine by Other (see comment). Avoid or Use Alternate Drug. Avoid coadministration of trilaciclib (OCT2, MATE1, and MATE-2K inhibitor) with substrates where minimal increased concentration in kidney or blood may lead to serious or life-threatening toxicities.

• vardenafil

  cimetidine will increase the level or effect of vardenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• verapamil

  cimetidine will increase the level or effect of verapamil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• vilazodone

  cimetidine increases levels of vilazodone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If intolerable adverse effects occur when coadministered with moderate CYP3A4 inhibitors, reduce daily dose to 20 mg.

• warfarin

  cimetidine will increase the level or effect of warfarin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

Monitor Closely (207)

• acalabrutinib

  cimetidine decreases levels of acalabrutinib by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Acalabrutinib solubility decreases with increasing gastric pH. Administer acalabrutinib 2 hr before an H2-receptor antagonist.
  
  acalabrutinib increases levels of cimetidine by Other (see comment). Use Caution/Monitor. Comment: Acalabrutinib may increase exposure to coadministered BCRP substrates by inhibition of intestinal BCRP.

• alfentanil

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

• alfuzosin

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

• alosetron

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

• amitriptyline

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

• apalutamide

  apalutamide will decrease the level or effect of cimetidine by increasing elimination. Use Caution/Monitor. Apalutamide weakly induces BCRP and may decrease systemic exposure of drugs that are BCRP substrates.

• armodafinil

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

• atazanavir

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

• atomoxetine

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

• avanafil

  cimetidine will increase the level or effect of avanafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may reduce avanafil clearance increasing systemic exposure to avanafil; increased levels may result in increased associated adverse events; the maximum recommended dose of STENDRA is 50 mg, not to exceed once every 24 hours for patients taking concomitant moderate CYP3A4 inhibitors

• avapritinib

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

• azelastine

  cimetidine increases effects of azelastine by decreasing metabolism. Use Caution/Monitor.

• bendamustine

  cimetidine increases levels of bendamustine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. Decreased conversion of bendamustine to active metabolites. Concentration of active metabolites of bendamustine may be decreased.

• benzhydrocodone/acetaminophen

  cimetidine will increase the level or effect of benzhydrocodone/acetaminophen by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone [benzhydrocodone is prodrug of hydrocodone]) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.

• berotralstat

  berotralstat will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Monitor or titrate P-gp substrate dose if coadministered.

• bexarotene

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

• bortezomib

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

• bosentan

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

• bosutinib

  bosutinib increases levels of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

• brexpiprazole

  cimetidine will increase the level or effect of brexpiprazole by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Administer a quarter of brexpiprazole dose if coadministered with a moderate CYP2D6 inhibitor PLUS a strong/moderate CYP3A4 inhibitor.
  
  cimetidine will increase the level or effect of brexpiprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Administer a quarter of brexpiprazole dose if coadministered with a moderate CYP3A4 inhibitor PLUS a strong/moderate CYP2D6 inhibitor.

• budesonide

  cimetidine decreases effects of budesonide by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Enteric-coated budesonide dissolves at pH >5.5. Also, dissolution of extended-release budesonide tablets is pH dependent. Coadministration with drugs that increase gastric pH may cause these budesonide products to prematurely dissolve, and possibly affect release properties and absorption of the drug in the duodenum.

• cabazitaxel

  cimetidine will increase the level or effect of cabazitaxel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Caution should be exercised with concomitant use of moderate CYP3A4 inhibitors.

• cabozantinib

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

• carbamazepine

  cimetidine will increase the level or effect of carbamazepine by decreasing metabolism. Modify Therapy/Monitor Closely. Monitor plasma levels when used concomitantly

• carbonyl iron

  cimetidine will decrease the level or effect of carbonyl iron by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• carmustine

  cimetidine, carmustine. Mechanism: decreasing metabolism. Use Caution/Monitor. Enhanced myelotoxicity.

• carvedilol

  cimetidine will increase the level or effect of carvedilol by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of carvedilol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• cefdinir

  cimetidine will decrease the level or effect of cefdinir by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• cefditoren

  cimetidine will decrease the level or effect of cefditoren by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• cefpodoxime

  cimetidine will decrease the level or effect of cefpodoxime by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• cefuroxime

  cimetidine will decrease the level or effect of cefuroxime by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• cevimeline

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

• chlordiazepoxide

  cimetidine increases levels of chlordiazepoxide by decreasing metabolism. Use Caution/Monitor.

• cilostazol

  cimetidine increases toxicity of cilostazol by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Consider decreasing cilostazol dose; moderate CYP2C19 inhibitors may increase serum levels of 3,4-dehydrocilostazol (active metabolite).

• citalopram

  cimetidine increases levels of citalopram by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. Citalopram 20 mg/day is the maximum recommended dose for patients taking CYP2C19 inhibitors because of the risk of QT prolongation.

• clarithromycin

  cimetidine will increase the level or effect of clarithromycin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  clarithromycin will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

• clomipramine

  cimetidine will increase the level or effect of clomipramine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of clomipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of clomipramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• clonazepam

  cimetidine increases levels of clonazepam by decreasing metabolism. Use Caution/Monitor.

• clopidogrel

  cimetidine decreases effects of clopidogrel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Clopidogrel efficacy may be reduced by drugs that inhibit CYP3A4. Inhibition of platelet aggregation by clopidogrel is entirely due to an active metabolite. Clopidogrel is metabolized to this active metabolite in part by CYP3A4. .

• clorazepate

  cimetidine increases levels of clorazepate by decreasing metabolism. Use Caution/Monitor.

• clozapine

  cimetidine will increase the level or effect of clozapine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• codeine

  cimetidine will increase the level or effect of codeine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Prevents conversion of codeine to its active metabolite morphine.

• conivaptan

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

• crizotinib

  cimetidine decreases levels of crizotinib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor. Drugs that elevate the gastric pH may decrease the solubility of crizotinib and subsequently reduce its bioavailability. However, no formal studies have been conducted. .

• dabrafenib

  cimetidine will decrease the level or effect of dabrafenib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor. Drugs that alter upper GI tract pH (eg, PPIs, H2-blockers, antacids) may decrease dabrafenib solubility and reduce its bioavailability

• desipramine

  cimetidine will increase the level or effect of desipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of desipramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• dexmethylphenidate

  cimetidine will increase the level or effect of dexmethylphenidate by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Applies only to extended release formulation

• dienogest/estradiol valerate

  cimetidine will increase the level or effect of dienogest/estradiol valerate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor for potential adverse effects such as nausea, irregular uterine bleeding, breast tenderness and headache.

• diltiazem

  cimetidine will increase the level or effect of diltiazem by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider alternatives to cimetidine in patients receiving diltiazem. If no alternative is available, monitor for the effects of diltiazem following cimetidine initiation/discontinuation.
  
  cimetidine will increase the level or effect of diltiazem by basic (cationic) drug competition for renal tubular clearance. Modify Therapy/Monitor Closely. Exercise caution when concomitantly using diltiazem with atazanavir. Consider reducing the diltiazem dose by 50%. ECG monitoring is recommended.

• disopyramide

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

• docetaxel

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

• donepezil

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

• doxepin

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

• doxepin cream

  cimetidine increases levels of doxepin cream by decreasing metabolism. Use Caution/Monitor.

• doxorubicin

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

• doxorubicin liposomal

  cimetidine will increase the level or effect of doxorubicin liposomal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• duloxetine

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

• dutasteride

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

• elagolix

  elagolix will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

• eliglustat

  eliglustat increases levels of cimetidine by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the P-gp substrate and titrate to clinical effect.

• eluxadoline

  cimetidine increases levels of eluxadoline by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. As a precautionary measure due to incomplete information on the metabolism of eluxadoline, use caution when coadministered with strong CYP2C19 inhibitors.
  
  eluxadoline increases levels of cimetidine by decreasing metabolism. Use Caution/Monitor. Eluxadoline may increase the systemic exposure of coadministered BCRP substrates.

• epirubicin

  cimetidine increases levels of epirubicin by decreasing metabolism. Use Caution/Monitor. Cimetidine increased the AUC of epirubicin by 50%. Cimetidine treatment should be stopped during treatment with epirubicin.

• eplerenone

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

• erdafitinib

  erdafitinib increases levels of cimetidine by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• erlotinib

  cimetidine decreases levels of erlotinib by Other (see comment). Use Caution/Monitor. Comment: Avoid combination when possible. If concurrent use is required erlotinib should be taken 10 hours after a H2-antagonist and at least 2 hours before the next dose of H2-antagonist.

• eslicarbazepine acetate

  eslicarbazepine acetate will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

• estrogens esterified

  cimetidine will increase the level or effect of estrogens esterified by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ethinylestradiol

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

• ethotoin

  cimetidine will increase the level or effect of ethotoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

• etoposide

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

• etravirine

  cimetidine will increase the level or effect of etravirine by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

• eucalyptus

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

• ferric maltol

  cimetidine will decrease the level or effect of ferric maltol by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• ferrous fumarate

  cimetidine will decrease the level or effect of ferrous fumarate by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• ferrous gluconate

  cimetidine will decrease the level or effect of ferrous gluconate by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• ferrous sulfate

  cimetidine will decrease the level or effect of ferrous sulfate by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• finerenone

  cimetidine 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.

• flecainide

  cimetidine will increase the level or effect of flecainide by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Flecainide dosage should be carefully titrated on initiation of therapy. Careful monitoring of flecainide plasma concentration should be instituted when cimetidine is coadministered or discontinued.

• flibanserin

  cimetidine 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.

• fluoxetine

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

• fluvastatin

  cimetidine increases levels of fluvastatin by decreasing metabolism. Use Caution/Monitor.

• fluvoxamine

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

• fosamprenavir

  cimetidine will decrease the level or effect of fosamprenavir by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• fosphenytoin

  cimetidine will increase the level or effect of fosphenytoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

• fostamatinib

  fostamatinib will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Concomitant use of fostamatinib may increase concentrations of P-gp substrates. Monitor for toxicities of the P-gp substrate drug that may require dosage reduction when given concurrently with fostamatinib.

• fostemsavir

  fostemsavir will increase the level or effect of cimetidine by Other (see comment). Modify Therapy/Monitor Closely. Fostemsavir inhibits BCRP transporters. If possible, avoid coadministration or modify dose of BCRP substrate coadministered with fostemsavir.

• galantamine

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

• gefitinib

  cimetidine decreases levels of gefitinib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor. Separate gefitinib and H2-antagonist doses by at least 6 hr.

• glecaprevir/pibrentasvir

  glecaprevir/pibrentasvir will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

• glipizide

  cimetidine will increase the level or effect of glipizide by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• glyburide

  cimetidine will increase the level or effect of glyburide by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• haloperidol

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

• hydrocodone

  cimetidine will increase the level or effect of hydrocodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.

• hydromorphone

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

• iloperidone

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

• imatinib

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

• imipramine

  cimetidine will increase the level or effect of imipramine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of imipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of imipramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• iron dextran complex

  cimetidine will decrease the level or effect of iron dextran complex by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• iron sucrose

  cimetidine will decrease the level or effect of iron sucrose by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• isoniazid

  isoniazid will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

• isradipine

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

• istradefylline

  istradefylline will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of P-gp substrates in clinical trials. Consider dose reduction of sensitive P-gp substrates.

• itraconazole

  cimetidine will decrease the level or effect of itraconazole by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Administer acid neutralizing medicines at least 2 hours before or 2 hours after itraconazole. When taking with cimetidine, administer with non-diet cola to increase GI acidity.

• ivacaftor

  cimetidine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification. .

• ketoconazole

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

• lapatinib

  cimetidine will decrease the level or effect of lapatinib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• ledipasvir/sofosbuvir

  cimetidine decreases levels of ledipasvir/sofosbuvir by Other (see comment). Use Caution/Monitor. Comment: Ledipasvir solubility decreases as pH increases; drugs that increase gastric pH are expected to decrease levels of ledipasvir; H2-receptor antagonists may be administered simultaneously with or 12 hr apart from ledipasvir/sofosbuvir at a dose that does not exceed doses comparable to famotidine 40 mg BID.

• lemborexant

  cimetidine 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.

• lidocaine

  cimetidine will increase the level or effect of lidocaine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• lomitapide

  lomitapide increases levels of cimetidine by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Consider reducing dose when used concomitantly with lomitapide.

• lomustine

  cimetidine, lomustine. Mechanism: decreasing metabolism. Use Caution/Monitor. Enhanced myelotoxicity.

• lonafarnib

  lonafarnib will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Lonafarnib is a weak P-gp inhibitor. Monitor for adverse reactions if coadministered with P-gp substrates where minimal concentration changes may lead to serious or life-threatening toxicities. Reduce P-gp substrate dose if needed.

• lurasidone

  cimetidine increases levels of lurasidone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Manufacturer recommends decreasing starting dose of lurasidone to 20 mg/day and maximum daily dose of lurasidone 80 mg when coadministered with moderate CYP3A4 inhibitors. Concurrent use may increase risk of lurasidone-related adverse reactions.

• mebendazole

  cimetidine increases levels of mebendazole by decreasing metabolism. Use Caution/Monitor.

• mefloquine

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

• memantine

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

• metformin

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

• methamphetamine

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

• methylphenidate

  cimetidine decreases effects of methylphenidate by enhancing GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Since the characteristics of methylphenidate extended release capsules (Ritalin LA) are pH dependent, coadministration of antacids or acid suppressants could alter the release of methylphenidate. Consider separating the administration of the antacid and the methylphenidate extended-release capsules may be avoided.

• metoprolol

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

• mexiletine

  cimetidine will increase the level or effect of mexiletine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of mexiletine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• midazolam intranasal

  cimetidine 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

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

• mizolastine

  cimetidine increases levels of mizolastine by decreasing metabolism. Use Caution/Monitor.

• morphine

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

• nateglinide

  cimetidine will increase the level or effect of nateglinide by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

• nebivolol

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

• nelfinavir

  cimetidine will increase the level or effect of nelfinavir by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• nicotine inhaled

  cimetidine increases levels of nicotine inhaled by decreasing renal clearance. Use Caution/Monitor.

• nicotine intranasal

  cimetidine increases levels of nicotine intranasal by decreasing metabolism. Use Caution/Monitor.
  
  cimetidine increases levels of nicotine intranasal by decreasing renal clearance. Use Caution/Monitor.

• nifedipine

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

• nilotinib

  cimetidine decreases levels of nilotinib by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Avoid this interaction by administering H2 antagonists 10 hr after or 2 hr before nilotinib.

• nimodipine

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

• nortriptyline

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

• olanzapine

  cimetidine will increase the level or effect of olanzapine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• oliceridine

  cimetidine will increase the level or effect of oliceridine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal.

• oxybutynin

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

• oxycodone

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

• oxymorphone

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

• paclitaxel

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

• paclitaxel protein bound

  cimetidine will increase the level or effect of paclitaxel protein bound by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• palbociclib

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

• parecoxib

  cimetidine will increase the level or effect of parecoxib by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of parecoxib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• paroxetine

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

• pentoxifylline

  cimetidine will increase the level or effect of pentoxifylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• phenytoin

  cimetidine will increase the level or effect of phenytoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

• pimozide

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

• pioglitazone

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

• polysaccharide iron

  cimetidine will decrease the level or effect of polysaccharide iron by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• ponatinib

  ponatinib increases levels of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
  
  ponatinib increases levels of cimetidine by Other (see comment). Use Caution/Monitor.

• posaconazole

  cimetidine will decrease the level or effect of posaconazole by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• pramipexole

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

• praziquantel

  cimetidine increases levels of praziquantel by decreasing metabolism. Use Caution/Monitor.

• propafenone

  cimetidine will increase the level or effect of propafenone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of propafenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• propranolol

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

• quinine

  cimetidine will increase the level or effect of quinine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of quinine by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• rabeprazole

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

• ramelteon

  cimetidine will increase the level or effect of ramelteon by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of ramelteon by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• rasagiline

  cimetidine will increase the level or effect of rasagiline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. Recommended dose of rasagiline is 0.5mg daily in combination with CYP1A2 inhibitors.

• regorafenib

  regorafenib will increase the level or effect of cimetidine by Other (see comment). Modify Therapy/Monitor Closely. Regorafenib likely inhibits BCRP (ABCG2) transport. Coadministration with a BCRP substrate may increase systemic exposure to the substrate and related toxicity.

• rilpivirine

  cimetidine will decrease the level or effect of rilpivirine by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Concurrent use, may cause treatment failure and/or the development of rilpivirine or NNRTI resistance owing to decreased levels. Administer H2 antagonists at least 12 hours before or at least 4 hours after rilpivirine.

• roflumilast

  cimetidine increases levels of roflumilast by Other (see comment). Modify Therapy/Monitor Closely. Comment: Coadministration with dual inhibitors of CYP3A4 and CYP1A2 may increase systemic exposure and result in increased adverse reactions.

• ropinirole

  cimetidine will increase the level or effect of ropinirole by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• rose hips

  cimetidine will decrease the level or effect of rose hips by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• ruxolitinib

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

• safinamide

  safinamide will increase the level or effect of cimetidine by Other (see comment). Use Caution/Monitor. Safinamide and its major metabolite may inhibit intestinal BCRP. Monitor BCRP substrates for increased pharmacologic or adverse effects.

• sarecycline

  sarecycline will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Monitor for toxicities of P-gp substrates that may require dosage reduction when coadministered with P-gp inhibitors.

• saxagliptin

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

• sildenafil

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

• sofosbuvir/velpatasvir

  cimetidine will decrease the level or effect of sofosbuvir/velpatasvir by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Velpatasvir solubility decreases as gastric pH increases (practically insoluble at pH >5). H2 receptor antagonists may be administered simultaneously with or 12 hr apart from sofosbuvir/velpatasvir at a dose that does not exceed doses comparable to famotidine 40 mg BID.
  
  sofosbuvir/velpatasvir will increase the level or effect of cimetidine by Other (see comment). Use Caution/Monitor. Velpatasvir is an inhibitor of the drug transporter BCRP. Coadministration may increase systemic exposure of drugs that are BCRP substrates.

• sonidegib

  cimetidine will increase the level or effect of sonidegib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid coadministration of sonidegib with moderate CYP3A4 inhibitors. If a moderate CYP3A inhibitor must be used, administer the moderate CYP3A inhibitor for <14 days and monitor closely for adverse reactions, particularly musculoskeletal adverse reactions.

• stiripentol

  stiripentol will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Consider reducing the dose of P-glycoprotein (P-gp) substrates, if adverse reactions are experienced when administered concomitantly with stiripentol.
  
  stiripentol will increase the level or effect of cimetidine by Other (see comment). Modify Therapy/Monitor Closely. Stiripentol is a BCRP transport inhibitor. Consider dosage reduction for BCRP substrates if adverse effects are experienced when coadministered.

• sufentanil

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

• sulfamethoxazole

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

• suvorexant

  cimetidine will increase the level or effect of suvorexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease suvorexant starting dose to 5 mg HS if coadministered with moderate CYP3A4 inhibitors

• tadalafil

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

• tafamidis

  tafamidis will increase the level or effect of cimetidine by Other (see comment). Use Caution/Monitor. Tafamidis inhibits breast cancer resistant protein (BCRP) in vitro and may increase exposure of BCRP substrates following tafamidis or tafamidis meglumine administration. Dosage adjustment of these BCRP substrates may be necessary.

• tafamidis meglumine

  tafamidis meglumine will increase the level or effect of cimetidine by Other (see comment). Use Caution/Monitor. Tafamidis inhibits breast cancer resistant protein (BCRP) in vitro and may increase exposure of BCRP substrates following tafamidis or tafamidis meglumine administration. Dosage adjustment of these BCRP substrates may be necessary.

• tamoxifen

  cimetidine, tamoxifen. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibition decreases metabolism of tamoxifen to N-desmethyl tamoxifen (active metabolite with similar biologic activity).

• tamsulosin

  cimetidine increases levels of tamsulosin by decreasing renal clearance. Use Caution/Monitor. Decreases tamsulosin clearance by 26% resulting in increased AUC (44%).
  
  cimetidine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• tazemetostat

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

• tenofovir DF

  cimetidine, tenofovir DF. Either increases levels of the other by decreasing renal clearance. Use Caution/Monitor.

• tetanus toxoid adsorbed or fluid

  cimetidine increases levels of tetanus toxoid adsorbed or fluid by decreasing metabolism. Use Caution/Monitor.

• theophylline

  cimetidine will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• timolol

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

• tinidazole

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

• tofacitinib

  cimetidine increases levels of tofacitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No specific dose adjustment recommended when tofacitinib coadministered with moderate CYP3A4 inhibitors; decrease tofacitinib dose if coadministered with both moderate CYP3A4 and potent CYP2C19 inhibitors.
  
  cimetidine increases levels of tofacitinib by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. No specific dose adjustment recommended when tofacitinib coadministered with potent CYP2C19 inhibitors; decrease tofacitinib dose if coadministered with both moderate CYP3A4 and potent CYP2C19 inhibitors .

• tolbutamide

  cimetidine will increase the level or effect of tolbutamide by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• tramadol

  cimetidine decreases effects of tramadol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Decreased conversion of tramadol to active metabolite.
  
  cimetidine decreases effects of tramadol by decreasing metabolism. Use Caution/Monitor. Decreased conversion of tramadol to active metabolite.

• trazodone

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

• triamterene

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

• trimethoprim

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

• tucatinib

  tucatinib will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Consider reducing the dosage of P-gp substrates, where minimal concentration changes may lead to serious or life-threatening toxicities.

• valacyclovir

  cimetidine increases levels of valacyclovir by decreasing renal clearance. Use Caution/Monitor.

• vandetanib

  vandetanib increases levels of cimetidine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Vandetanib inhibits the uptake of substrates of organic cation transporter type 2 (OCT2).

• verapamil

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

• vinblastine

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

• vincristine

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

• vincristine liposomal

  cimetidine will increase the level or effect of vincristine liposomal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• vinorelbine

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

• vismodegib

  cimetidine will decrease the level or effect of vismodegib by Other (see comment). Use Caution/Monitor. Drugs that increase gastric pH alter vismodegib solubility and therefore reduce bioavailability; effect on efficacy unknown

• warfarin

  cimetidine will increase the level or effect of warfarin by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of warfarin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

• zaleplon

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

• ziprasidone

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

• zolmitriptan

  cimetidine increases levels of zolmitriptan by unknown mechanism. Modify Therapy/Monitor Closely. Half-life and blood levels of zolmitriptan and its active N-desmethyl metabolite are approximately doubled when coadministered with cimetidine; limit zolmitriptan to 2.5 mg/dose and 5 mg/day.

• zolpidem

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

• zonisamide

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

Minor (65)

• alosetron

  cimetidine will increase the level or effect of alosetron by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• amobarbital

  amobarbital will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• antipyrine

  cimetidine will increase the level or effect of antipyrine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• aripiprazole

  cimetidine will increase the level or effect of aripiprazole by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• armodafinil

  armodafinil will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• asenapine

  cimetidine will increase the level or effect of asenapine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• blessed thistle

  blessed thistle decreases effects of cimetidine by pharmacodynamic antagonism. Minor/Significance Unknown. Theoretical interaction.

• bosentan

  cimetidine will increase the level or effect of bosentan by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• butabarbital

  butabarbital will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• butalbital

  butalbital will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• caffeine

  cimetidine will increase the level or effect of caffeine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• celecoxib

  cimetidine will increase the level or effect of celecoxib by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• chlorpromazine

  cimetidine will increase the level or effect of chlorpromazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• cyanocobalamin

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

• devil's claw

  devil's claw decreases effects of cimetidine by pharmacodynamic antagonism. Minor/Significance Unknown.

• dextroamphetamine

  cimetidine will increase the level or effect of dextroamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• dextromethorphan

  cimetidine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• diclofenac

  cimetidine will increase the level or effect of diclofenac by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• digoxin

  cimetidine will increase the level or effect of digoxin by increasing gastric pH. Applies only to oral form of both agents. Minor/Significance Unknown.
  
  cimetidine will increase the level or effect of digoxin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• donepezil

  cimetidine will increase the level or effect of donepezil by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• efavirenz

  efavirenz will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• eltrombopag

  cimetidine will increase the level or effect of eltrombopag by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.
  
  cimetidine will increase the level or effect of eltrombopag by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• encainide

  cimetidine will increase the level or effect of encainide by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• etravirine

  etravirine will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• famciclovir

  cimetidine, famciclovir. aldehyde dehydrogenase inhibition. Minor/Significance Unknown. The conversion of 6-deoxy penciclovir to penciclovir is catalyzed by aldehyde oxidase. Interactions with other drugs metabolized by this enzyme and/or inhibiting this enzyme could potentially occur. Clinical interaction studies of famciclovir with cimetidine did not show relevant effects on the formation of penciclovir.

• felbamate

  felbamate will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• felodipine

  felodipine will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• fesoterodine

  cimetidine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• fluconazole

  fluconazole will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• fluphenazine

  cimetidine will increase the level or effect of fluphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• flurbiprofen

  cimetidine will increase the level or effect of flurbiprofen by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• fluvastatin

  cimetidine will increase the level or effect of fluvastatin by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• galantamine

  cimetidine will increase the level or effect of galantamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• green tea

  cimetidine will increase the level or effect of green tea by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown. Green tea may contain caffeine. CYP1A2 inhibitors may inhibit the hepatic oxidative metabolism of caffeine.

• ibuprofen

  cimetidine will increase the level or effect of ibuprofen by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• ibuprofen IV

  cimetidine will increase the level or effect of ibuprofen IV by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• loratadine

  cimetidine will increase the level or effect of loratadine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• losartan

  cimetidine will increase the level or effect of losartan by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown. May inhibit the conversion of losartan to its active metabolite E-3174. Importance of interaction not established; monitor individual therapeutic response to determine losartan dosage.

• modafinil

  modafinil will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• ospemifene

  cimetidine increases levels of ospemifene by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• oxcarbazepine

  oxcarbazepine will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• parecoxib

  parecoxib will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• pefloxacin

  cimetidine increases levels of pefloxacin by decreasing metabolism. Minor/Significance Unknown.

• pentobarbital

  pentobarbital will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• perhexiline

  cimetidine will increase the level or effect of perhexiline by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• perphenazine

  cimetidine will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• phenobarbital

  phenobarbital will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• phytoestrogens

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

• piroxicam

  cimetidine will increase the level or effect of piroxicam by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• primidone

  primidone will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• prochlorperazine

  cimetidine will increase the level or effect of prochlorperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• promazine

  cimetidine will increase the level or effect of promazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• promethazine

  cimetidine will increase the level or effect of promethazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• ramelteon

  cimetidine will increase the level or effect of ramelteon by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• rifampin

  rifampin will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• riluzole

  cimetidine will increase the level or effect of riluzole by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• risperidone

  cimetidine will increase the level or effect of risperidone by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• secobarbital

  secobarbital will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• sulfamethoxazole

  cimetidine will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• tolbutamide

  cimetidine will increase the level or effect of tolbutamide by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• tolterodine

  cimetidine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• trifluoperazine

  cimetidine will increase the level or effect of trifluoperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• tropisetron

  cimetidine will increase the level or effect of tropisetron by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• varenicline

  cimetidine increases levels of varenicline by decreasing renal clearance. Minor/Significance Unknown.

• voriconazole

  voriconazole will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.
  
  cimetidine will increase the level or effect of voriconazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• acalabrutinib

  Monitor Closely (2)acalabrutinib increases levels of cimetidine by Other (see comment). Use Caution/Monitor. Comment: Acalabrutinib may increase exposure to coadministered BCRP substrates by inhibition of intestinal BCRP.
  
  cimetidine decreases levels of acalabrutinib by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Acalabrutinib solubility decreases with increasing gastric pH. Administer acalabrutinib 2 hr before an H2-receptor antagonist.

• alfentanil

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

• alfuzosin

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

• alitretinoin

  Serious - Use Alternative (1)cimetidine will increase the level or effect of alitretinoin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• alosetron

  Monitor Closely (1)cimetidine will increase the level or effect of alosetron by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will increase the level or effect of alosetron by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug.Minor (1)cimetidine will increase the level or effect of alosetron by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• alprazolam

  Serious - Use Alternative (1)cimetidine will increase the level or effect of alprazolam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• amiodarone

  Serious - Use Alternative (1)cimetidine will increase the level or effect of amiodarone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• amitriptyline

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

• amobarbital

  Minor (1)amobarbital will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• antipyrine

  Minor (1)cimetidine will increase the level or effect of antipyrine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• apalutamide

  Monitor Closely (1)apalutamide will decrease the level or effect of cimetidine by increasing elimination. Use Caution/Monitor. Apalutamide weakly induces BCRP and may decrease systemic exposure of drugs that are BCRP substrates.

• aprepitant

  Serious - Use Alternative (1)cimetidine will increase the level or effect of aprepitant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• aripiprazole

  Serious - Use Alternative (1)cimetidine will increase the level or effect of aripiprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)cimetidine will increase the level or effect of aripiprazole by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• armodafinil

  Monitor Closely (1)cimetidine will increase the level or effect of armodafinil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)armodafinil will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• artemether/lumefantrine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of artemether/lumefantrine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• asenapine

  Minor (1)cimetidine will increase the level or effect of asenapine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• atazanavir

  Monitor Closely (1)cimetidine will increase the level or effect of atazanavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will decrease the level or effect of atazanavir by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Atazanavir solubility decreases as pH increases. Substantially reduced plasma concentrations of atazanavir are expected if H2-receptor antagonists (H2RA) are coadministered. For treatment-naïve patients, take atazanavir simultaneously with the H2RA or at least 10 h afterwards. See dosage adjustment recommendations if coadministered in treatment-experienced patients.

• atomoxetine

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

• atorvastatin

  Serious - Use Alternative (1)cimetidine will increase the level or effect of atorvastatin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• avanafil

  Monitor Closely (1)cimetidine will increase the level or effect of avanafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may reduce avanafil clearance increasing systemic exposure to avanafil; increased levels may result in increased associated adverse events; the maximum recommended dose of STENDRA is 50 mg, not to exceed once every 24 hours for patients taking concomitant moderate CYP3A4 inhibitors

• avapritinib

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

• axitinib

  Serious - Use Alternative (1)cimetidine increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with moderate CYP3A4 inhibitors, monitor closely and reduce dose if necessary .

• azelastine

  Monitor Closely (1)cimetidine increases effects of azelastine by decreasing metabolism. Use Caution/Monitor.

• bazedoxifene/conjugated estrogens

  Serious - Use Alternative (1)cimetidine will increase the level or effect of bazedoxifene/conjugated estrogens by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• belladonna and opium

  Serious - Use Alternative (1)cimetidine increases effects of belladonna and opium by decreasing metabolism. Avoid or Use Alternate Drug.

• bendamustine

  Monitor Closely (1)cimetidine increases levels of bendamustine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. Decreased conversion of bendamustine to active metabolites. Concentration of active metabolites of bendamustine may be decreased.

• benzhydrocodone/acetaminophen

  Monitor Closely (1)cimetidine will increase the level or effect of benzhydrocodone/acetaminophen by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone [benzhydrocodone is prodrug of hydrocodone]) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.

• berotralstat

  Monitor Closely (1)berotralstat will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Monitor or titrate P-gp substrate dose if coadministered.

• bexarotene

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

• blessed thistle

  Minor (1)blessed thistle decreases effects of cimetidine by pharmacodynamic antagonism. Minor/Significance Unknown. Theoretical interaction.

• bortezomib

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

• bosentan

  Monitor Closely (1)cimetidine will increase the level or effect of bosentan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)cimetidine will increase the level or effect of bosentan by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• bosutinib

  Monitor Closely (1)bosutinib increases levels of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine increases levels of bosutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• brexpiprazole

  Monitor Closely (2)cimetidine will increase the level or effect of brexpiprazole by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Administer a quarter of brexpiprazole dose if coadministered with a moderate CYP2D6 inhibitor PLUS a strong/moderate CYP3A4 inhibitor.
  
  cimetidine will increase the level or effect of brexpiprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Administer a quarter of brexpiprazole dose if coadministered with a moderate CYP3A4 inhibitor PLUS a strong/moderate CYP2D6 inhibitor.

• budesonide

  Monitor Closely (1)cimetidine decreases effects of budesonide by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Enteric-coated budesonide dissolves at pH >5.5. Also, dissolution of extended-release budesonide tablets is pH dependent. Coadministration with drugs that increase gastric pH may cause these budesonide products to prematurely dissolve, and possibly affect release properties and absorption of the drug in the duodenum.Serious - Use Alternative (1)cimetidine will increase the level or effect of budesonide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• buprenorphine

  Serious - Use Alternative (1)cimetidine increases effects of buprenorphine by decreasing metabolism. Avoid or Use Alternate Drug.

• buprenorphine buccal

  Serious - Use Alternative (1)cimetidine increases effects of buprenorphine buccal by decreasing metabolism. Avoid or Use Alternate Drug.

• buspirone

  Serious - Use Alternative (1)cimetidine will increase the level or effect of buspirone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• butabarbital

  Minor (1)butabarbital will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• butalbital

  Minor (1)butalbital will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• butorphanol

  Serious - Use Alternative (1)cimetidine increases effects of butorphanol by decreasing metabolism. Avoid or Use Alternate Drug.

• cabazitaxel

  Monitor Closely (1)cimetidine will increase the level or effect of cabazitaxel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Caution should be exercised with concomitant use of moderate CYP3A4 inhibitors.

• cabozantinib

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

• caffeine

  Minor (1)cimetidine will increase the level or effect of caffeine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• carbamazepine

  Monitor Closely (1)cimetidine will increase the level or effect of carbamazepine by decreasing metabolism. Modify Therapy/Monitor Closely. Monitor plasma levels when used concomitantly

• carbonyl iron

  Monitor Closely (1)cimetidine will decrease the level or effect of carbonyl iron by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• carmustine

  Monitor Closely (1)cimetidine, carmustine. Mechanism: decreasing metabolism. Use Caution/Monitor. Enhanced myelotoxicity.

• carvedilol

  Monitor Closely (2)cimetidine will increase the level or effect of carvedilol by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of carvedilol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• cefdinir

  Monitor Closely (1)cimetidine will decrease the level or effect of cefdinir by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• cefditoren

  Monitor Closely (1)cimetidine will decrease the level or effect of cefditoren by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• cefpodoxime

  Monitor Closely (1)cimetidine will decrease the level or effect of cefpodoxime by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• cefuroxime

  Monitor Closely (1)cimetidine will decrease the level or effect of cefuroxime by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• celecoxib

  Minor (1)cimetidine will increase the level or effect of celecoxib by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• cevimeline

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

• chlordiazepoxide

  Monitor Closely (1)cimetidine increases levels of chlordiazepoxide by decreasing metabolism. Use Caution/Monitor.

• chloroquine

  Serious - Use Alternative (1)cimetidine increases levels of chloroquine by decreasing metabolism. Avoid or Use Alternate Drug.

• chlorpromazine

  Minor (1)cimetidine will increase the level or effect of chlorpromazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• cilostazol

  Monitor Closely (1)cimetidine increases toxicity of cilostazol by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Consider decreasing cilostazol dose; moderate CYP2C19 inhibitors may increase serum levels of 3,4-dehydrocilostazol (active metabolite).Serious - Use Alternative (1)cimetidine will increase the level or effect of cilostazol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• cinacalcet

  Serious - Use Alternative (1)cimetidine will increase the level or effect of cinacalcet by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• citalopram

  Monitor Closely (1)cimetidine increases levels of citalopram by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. Citalopram 20 mg/day is the maximum recommended dose for patients taking CYP2C19 inhibitors because of the risk of QT prolongation.

• clarithromycin

  Monitor Closely (2)clarithromycin will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of clarithromycin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• clomipramine

  Monitor Closely (3)cimetidine will increase the level or effect of clomipramine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of clomipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of clomipramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• clonazepam

  Monitor Closely (1)cimetidine increases levels of clonazepam by decreasing metabolism. Use Caution/Monitor.

• clopidogrel

  Monitor Closely (1)cimetidine decreases effects of clopidogrel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Clopidogrel efficacy may be reduced by drugs that inhibit CYP3A4. Inhibition of platelet aggregation by clopidogrel is entirely due to an active metabolite. Clopidogrel is metabolized to this active metabolite in part by CYP3A4. .Serious - Use Alternative (1)cimetidine decreases effects of clopidogrel by affecting hepatic enzyme CYP2C19 metabolism. Avoid or Use Alternate Drug. Clopidogrel efficacy may be reduced by drugs that inhibit CYP2C19. Inhibition of platelet aggregation by clopidogrel is entirely due to an active metabolite. Clopidogrel is metabolized to this active metabolite in part by CYP2C19. .

• clorazepate

  Monitor Closely (1)cimetidine increases levels of clorazepate by decreasing metabolism. Use Caution/Monitor.

• clozapine

  Monitor Closely (1)cimetidine will increase the level or effect of clozapine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will increase the level or effect of clozapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• codeine

  Monitor Closely (1)cimetidine will increase the level or effect of codeine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Prevents conversion of codeine to its active metabolite morphine.

• conivaptan

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

• conjugated estrogens

  Serious - Use Alternative (1)cimetidine will increase the level or effect of conjugated estrogens by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• conjugated estrogens, vaginal

  Serious - Use Alternative (1)cimetidine will increase the level or effect of conjugated estrogens, vaginal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• crizotinib

  Monitor Closely (1)cimetidine decreases levels of crizotinib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor. Drugs that elevate the gastric pH may decrease the solubility of crizotinib and subsequently reduce its bioavailability. However, no formal studies have been conducted. .

• cyanocobalamin

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

• cyclosporine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of cyclosporine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• dabrafenib

  Monitor Closely (1)cimetidine will decrease the level or effect of dabrafenib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor. Drugs that alter upper GI tract pH (eg, PPIs, H2-blockers, antacids) may decrease dabrafenib solubility and reduce its bioavailability

• darifenacin

  Serious - Use Alternative (1)cimetidine will increase the level or effect of darifenacin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• darolutamide

  Serious - Use Alternative (1)darolutamide will increase the level or effect of cimetidine by Other (see comment). Avoid or Use Alternate Drug. Darolutamide is a BCRP inhibitor. Avoid coadministration with BCRP inhibitors. If use is unavoidable, closely monitor for adverse reactions and consider dose reduction of BCRP substrate drug (refer BCRP substrate prescribing information).

• darunavir

  Serious - Use Alternative (1)cimetidine will increase the level or effect of darunavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• dasatinib

  Serious - Use Alternative (2)cimetidine will increase the level or effect of dasatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  cimetidine will decrease the level or effect of dasatinib by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• desipramine

  Monitor Closely (2)cimetidine will increase the level or effect of desipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of desipramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• devil's claw

  Minor (1)devil's claw decreases effects of cimetidine by pharmacodynamic antagonism. Minor/Significance Unknown.

• dexamethasone

  Serious - Use Alternative (1)cimetidine will increase the level or effect of dexamethasone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• dexmethylphenidate

  Monitor Closely (1)cimetidine will increase the level or effect of dexmethylphenidate by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Applies only to extended release formulation

• dextroamphetamine

  Minor (1)cimetidine will increase the level or effect of dextroamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• dextromethorphan

  Minor (1)cimetidine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• diazepam

  Serious - Use Alternative (1)cimetidine will increase the level or effect of diazepam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• diclofenac

  Minor (1)cimetidine will increase the level or effect of diclofenac by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• dienogest/estradiol valerate

  Monitor Closely (1)cimetidine will increase the level or effect of dienogest/estradiol valerate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor for potential adverse effects such as nausea, irregular uterine bleeding, breast tenderness and headache.

• difenoxin hcl

  Serious - Use Alternative (1)cimetidine increases effects of difenoxin hcl by decreasing metabolism. Avoid or Use Alternate Drug.

• digoxin

  Minor (2)cimetidine will increase the level or effect of digoxin by increasing gastric pH. Applies only to oral form of both agents. Minor/Significance Unknown.
  
  cimetidine will increase the level or effect of digoxin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

• dihydroergotamine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of dihydroergotamine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• dihydroergotamine intranasal

  Serious - Use Alternative (1)cimetidine will increase the level or effect of dihydroergotamine intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• diltiazem

  Monitor Closely (2)cimetidine will increase the level or effect of diltiazem by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider alternatives to cimetidine in patients receiving diltiazem. If no alternative is available, monitor for the effects of diltiazem following cimetidine initiation/discontinuation.
  
  cimetidine will increase the level or effect of diltiazem by basic (cationic) drug competition for renal tubular clearance. Modify Therapy/Monitor Closely. Exercise caution when concomitantly using diltiazem with atazanavir. Consider reducing the diltiazem dose by 50%. ECG monitoring is recommended.

• diphenoxylate hcl

  Serious - Use Alternative (1)cimetidine increases effects of diphenoxylate hcl by decreasing metabolism. Avoid or Use Alternate Drug.

• disopyramide

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

• docetaxel

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

• dofetilide

  Contraindicated (1)cimetidine increases levels of dofetilide by decreasing renal clearance. Contraindicated. Risk of prolonged QTc interval.Serious - Use Alternative (1)cimetidine will increase the level or effect of dofetilide by basic (cationic) drug competition for renal tubular clearance. Avoid or Use Alternate Drug.

• donepezil

  Monitor Closely (1)cimetidine will increase the level or effect of donepezil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)cimetidine will increase the level or effect of donepezil by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• doxepin

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

• doxepin cream

  Monitor Closely (1)cimetidine increases levels of doxepin cream by decreasing metabolism. Use Caution/Monitor.

• doxorubicin

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

• doxorubicin liposomal

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

• dronedarone

  Serious - Use Alternative (1)cimetidine will increase the level or effect of dronedarone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• duloxetine

  Monitor Closely (1)cimetidine will increase the level or effect of duloxetine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will increase the level or effect of duloxetine by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug.

• dutasteride

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

• efavirenz

  Minor (1)efavirenz will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• elagolix

  Monitor Closely (1)elagolix will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

• eletriptan

  Serious - Use Alternative (1)cimetidine will increase the level or effect of eletriptan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• eliglustat

  Contraindicated (1)cimetidine increases levels of eliglustat by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated. If coadministered with strong or moderate CYP2D6 inhibitors, reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive and intermediate metabolizers; eliglustat is contraindiated if strong or moderate CYP2D6 inhibitors are given concomitantly with strong or moderate CYP3A inhibitors.Monitor Closely (1)eliglustat increases levels of cimetidine by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the P-gp substrate and titrate to clinical effect.Serious - Use Alternative (1)cimetidine increases levels of eliglustat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Moderate CYP3A4 inhibitors are not recommended with eliglustat poor or intermediate metabolizers; reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive metabolizers .

• eltrombopag

  Minor (2)cimetidine will increase the level or effect of eltrombopag by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.
  
  cimetidine will increase the level or effect of eltrombopag by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• eluxadoline

  Monitor Closely (2)eluxadoline increases levels of cimetidine by decreasing metabolism. Use Caution/Monitor. Eluxadoline may increase the systemic exposure of coadministered BCRP substrates.
  
  cimetidine increases levels of eluxadoline by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. As a precautionary measure due to incomplete information on the metabolism of eluxadoline, use caution when coadministered with strong CYP2C19 inhibitors.

• encainide

  Minor (1)cimetidine will increase the level or effect of encainide by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• epirubicin

  Monitor Closely (1)cimetidine increases levels of epirubicin by decreasing metabolism. Use Caution/Monitor. Cimetidine increased the AUC of epirubicin by 50%. Cimetidine treatment should be stopped during treatment with epirubicin.

• eplerenone

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

• erdafitinib

  Monitor Closely (1)erdafitinib increases levels of cimetidine by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.Serious - Use Alternative (1)erdafitinib will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ergotamine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of ergotamine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• erlotinib

  Monitor Closely (1)cimetidine decreases levels of erlotinib by Other (see comment). Use Caution/Monitor. Comment: Avoid combination when possible. If concurrent use is required erlotinib should be taken 10 hours after a H2-antagonist and at least 2 hours before the next dose of H2-antagonist.

• erythromycin base

  Serious - Use Alternative (1)cimetidine will increase the level or effect of erythromycin base by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• erythromycin ethylsuccinate

  Serious - Use Alternative (1)cimetidine will increase the level or effect of erythromycin ethylsuccinate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• erythromycin lactobionate

  Serious - Use Alternative (1)cimetidine will increase the level or effect of erythromycin lactobionate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• erythromycin stearate

  Serious - Use Alternative (1)cimetidine will increase the level or effect of erythromycin stearate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• eslicarbazepine acetate

  Monitor Closely (1)eslicarbazepine acetate will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

• estradiol

  Serious - Use Alternative (1)cimetidine will increase the level or effect of estradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• estrogens conjugated synthetic

  Serious - Use Alternative (1)cimetidine will increase the level or effect of estrogens conjugated synthetic by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• estrogens esterified

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

• estropipate

  Serious - Use Alternative (1)cimetidine will increase the level or effect of estropipate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• ethinylestradiol

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

• ethotoin

  Monitor Closely (1)cimetidine will increase the level or effect of ethotoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

• etoposide

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

• etravirine

  Monitor Closely (1)cimetidine will increase the level or effect of etravirine by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will increase the level or effect of etravirine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)etravirine will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• eucalyptus

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

• everolimus

  Serious - Use Alternative (1)cimetidine will increase the level or effect of everolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• famciclovir

  Minor (1)cimetidine, famciclovir. aldehyde dehydrogenase inhibition. Minor/Significance Unknown. The conversion of 6-deoxy penciclovir to penciclovir is catalyzed by aldehyde oxidase. Interactions with other drugs metabolized by this enzyme and/or inhibiting this enzyme could potentially occur. Clinical interaction studies of famciclovir with cimetidine did not show relevant effects on the formation of penciclovir.

• fedratinib

  Serious - Use Alternative (1)cimetidine will increase the level or effect of fedratinib by Other (see comment). Avoid or Use Alternate Drug. Avoid coadministration of fedratinib (a CYP3A4 and CYP2C19 substrate) with dual CYP3A4 and CYP2C19 inhibitor. Effect of coadministration of a dual CYP3A4 and CYP2C19 inhibitor with fedratinib has not been studied.

• felbamate

  Minor (1)felbamate will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• felodipine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of felodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)felodipine will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• fentanyl

  Serious - Use Alternative (1)cimetidine will increase the level or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl intranasal

  Serious - Use Alternative (1)cimetidine will increase the level or effect of fentanyl intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl transdermal

  Serious - Use Alternative (1)cimetidine will increase the level or effect of fentanyl transdermal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl transmucosal

  Serious - Use Alternative (1)cimetidine will increase the level or effect of fentanyl transmucosal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• ferric maltol

  Monitor Closely (1)cimetidine will decrease the level or effect of ferric maltol by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• ferrous fumarate

  Monitor Closely (1)cimetidine will decrease the level or effect of ferrous fumarate by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• ferrous gluconate

  Monitor Closely (1)cimetidine will decrease the level or effect of ferrous gluconate by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• ferrous sulfate

  Monitor Closely (1)cimetidine will decrease the level or effect of ferrous sulfate by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• fesoterodine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)cimetidine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• finerenone

  Monitor Closely (1)cimetidine 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.

• flecainide

  Monitor Closely (1)cimetidine will increase the level or effect of flecainide by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Flecainide dosage should be carefully titrated on initiation of therapy. Careful monitoring of flecainide plasma concentration should be instituted when cimetidine is coadministered or discontinued.

• flibanserin

  Monitor Closely (1)cimetidine 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.

• fluconazole

  Minor (1)fluconazole will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• fludrocortisone

  Serious - Use Alternative (1)cimetidine will increase the level or effect of fludrocortisone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• fluoxetine

  Monitor Closely (1)cimetidine will increase the level or effect of fluoxetine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)fluoxetine will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Avoid or Use Alternate Drug.

• fluphenazine

  Minor (1)cimetidine will increase the level or effect of fluphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• flurbiprofen

  Minor (1)cimetidine will increase the level or effect of flurbiprofen by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• fluvastatin

  Monitor Closely (1)cimetidine increases levels of fluvastatin by decreasing metabolism. Use Caution/Monitor.Minor (1)cimetidine will increase the level or effect of fluvastatin by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• fluvoxamine

  Monitor Closely (1)cimetidine will increase the level or effect of fluvoxamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)fluvoxamine will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Avoid or Use Alternate Drug.

• fosamprenavir

  Monitor Closely (1)cimetidine will decrease the level or effect of fosamprenavir by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will increase the level or effect of fosamprenavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• fosphenytoin

  Monitor Closely (1)cimetidine will increase the level or effect of fosphenytoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

• fostamatinib

  Monitor Closely (1)fostamatinib will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Concomitant use of fostamatinib may increase concentrations of P-gp substrates. Monitor for toxicities of the P-gp substrate drug that may require dosage reduction when given concurrently with fostamatinib.

• fostemsavir

  Monitor Closely (1)fostemsavir will increase the level or effect of cimetidine by Other (see comment). Modify Therapy/Monitor Closely. Fostemsavir inhibits BCRP transporters. If possible, avoid coadministration or modify dose of BCRP substrate coadministered with fostemsavir.

• galantamine

  Monitor Closely (1)cimetidine will increase the level or effect of galantamine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)cimetidine will increase the level or effect of galantamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• gefitinib

  Monitor Closely (1)cimetidine decreases levels of gefitinib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor. Separate gefitinib and H2-antagonist doses by at least 6 hr.

• glecaprevir/pibrentasvir

  Monitor Closely (1)glecaprevir/pibrentasvir will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

• glipizide

  Monitor Closely (1)cimetidine will increase the level or effect of glipizide by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• glyburide

  Monitor Closely (1)cimetidine will increase the level or effect of glyburide by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• green tea

  Minor (1)cimetidine will increase the level or effect of green tea by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown. Green tea may contain caffeine. CYP1A2 inhibitors may inhibit the hepatic oxidative metabolism of caffeine.

• haloperidol

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

• hydrocodone

  Monitor Closely (1)cimetidine will increase the level or effect of hydrocodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.

• hydrocortisone

  Serious - Use Alternative (1)cimetidine will increase the level or effect of hydrocortisone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• hydromorphone

  Monitor Closely (1)cimetidine will increase the level or effect of hydromorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine increases effects of hydromorphone by decreasing metabolism. Avoid or Use Alternate Drug.

• hydroxyprogesterone caproate

  Serious - Use Alternative (1)cimetidine will increase the level or effect of hydroxyprogesterone caproate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• ibuprofen

  Minor (1)cimetidine will increase the level or effect of ibuprofen by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• ibuprofen IV

  Minor (1)cimetidine will increase the level or effect of ibuprofen IV by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• iloperidone

  Monitor Closely (1)cimetidine will increase the level or effect of iloperidone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will increase the level or effect of iloperidone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• imatinib

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

• imipramine

  Monitor Closely (3)cimetidine will increase the level or effect of imipramine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of imipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of imipramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• indinavir

  Serious - Use Alternative (2)cimetidine will increase the level or effect of indinavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  cimetidine will decrease the level or effect of indinavir by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• infigratinib

  Serious - Use Alternative (1)cimetidine will decrease the level or effect of infigratinib by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. If use with an acid-reducing agent cannot be avoided, administer infigratinib 2 hr before or 10 hr after administration of a H2-antagonist.

• irinotecan

  Serious - Use Alternative (1)cimetidine will increase the level or effect of irinotecan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• irinotecan liposomal

  Serious - Use Alternative (1)cimetidine will increase the level or effect of irinotecan liposomal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• iron dextran complex

  Monitor Closely (1)cimetidine will decrease the level or effect of iron dextran complex by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• iron sucrose

  Monitor Closely (1)cimetidine will decrease the level or effect of iron sucrose by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• isoniazid

  Monitor Closely (1)isoniazid will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

• isradipine

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

• istradefylline

  Monitor Closely (1)istradefylline will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of P-gp substrates in clinical trials. Consider dose reduction of sensitive P-gp substrates.

• itraconazole

  Monitor Closely (1)cimetidine will decrease the level or effect of itraconazole by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Administer acid neutralizing medicines at least 2 hours before or 2 hours after itraconazole. When taking with cimetidine, administer with non-diet cola to increase GI acidity.

• ivabradine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of ivabradine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of ivabradine with moderate CYP3A4 inhibitors.

• ivacaftor

  Monitor Closely (1)cimetidine increases levels of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification. .Serious - Use Alternative (1)ivacaftor increases levels of cimetidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. Ivacaftor and its M1 metabolite has the potential to inhibit P-gp; may significantly increase systemic exposure to sensitive P-gp substrates with a narrow therapeutic index.

• ixabepilone

  Serious - Use Alternative (1)cimetidine will increase the level or effect of ixabepilone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• ketoconazole

  Monitor Closely (1)cimetidine will increase the level or effect of ketoconazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will decrease the level or effect of ketoconazole by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• lapatinib

  Monitor Closely (1)cimetidine will decrease the level or effect of lapatinib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• lasmiditan

  Serious - Use Alternative (1)lasmiditan increases levels of cimetidine by Other (see comment). Avoid or Use Alternate Drug. Comment: Lasmiditan inhibits BCRP in vitro. Avoid coadministration of lasmiditan with BCRP substrates.

• ledipasvir/sofosbuvir

  Monitor Closely (1)cimetidine decreases levels of ledipasvir/sofosbuvir by Other (see comment). Use Caution/Monitor. Comment: Ledipasvir solubility decreases as pH increases; drugs that increase gastric pH are expected to decrease levels of ledipasvir; H2-receptor antagonists may be administered simultaneously with or 12 hr apart from ledipasvir/sofosbuvir at a dose that does not exceed doses comparable to famotidine 40 mg BID.

• lemborexant

  Monitor Closely (1)cimetidine 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.

• levorphanol

  Serious - Use Alternative (1)cimetidine increases effects of levorphanol by decreasing metabolism. Avoid or Use Alternate Drug.

• lidocaine

  Monitor Closely (1)cimetidine will increase the level or effect of lidocaine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• lomitapide

  Contraindicated (1)cimetidine increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Increases lomitapide levels several folds.Monitor Closely (1)lomitapide increases levels of cimetidine by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Consider reducing dose when used concomitantly with lomitapide.

• lomustine

  Monitor Closely (1)cimetidine, lomustine. Mechanism: decreasing metabolism. Use Caution/Monitor. Enhanced myelotoxicity.

• lonafarnib

  Monitor Closely (1)lonafarnib will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Lonafarnib is a weak P-gp inhibitor. Monitor for adverse reactions if coadministered with P-gp substrates where minimal concentration changes may lead to serious or life-threatening toxicities. Reduce P-gp substrate dose if needed.Serious - Use Alternative (1)cimetidine 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.

• lopinavir

  Serious - Use Alternative (1)cimetidine will increase the level or effect of lopinavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• loratadine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of loratadine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)cimetidine will increase the level or effect of loratadine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• losartan

  Minor (1)cimetidine will increase the level or effect of losartan by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown. May inhibit the conversion of losartan to its active metabolite E-3174. Importance of interaction not established; monitor individual therapeutic response to determine losartan dosage.

• lovastatin

  Serious - Use Alternative (1)cimetidine will increase the level or effect of lovastatin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• lumefantrine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of lumefantrine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• lurasidone

  Monitor Closely (1)cimetidine increases levels of lurasidone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Manufacturer recommends decreasing starting dose of lurasidone to 20 mg/day and maximum daily dose of lurasidone 80 mg when coadministered with moderate CYP3A4 inhibitors. Concurrent use may increase risk of lurasidone-related adverse reactions.

• maraviroc

  Serious - Use Alternative (1)cimetidine will increase the level or effect of maraviroc by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• mebendazole

  Monitor Closely (1)cimetidine increases levels of mebendazole by decreasing metabolism. Use Caution/Monitor.

• mefloquine

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

• memantine

  Monitor Closely (1)cimetidine will increase the level or effect of memantine by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• meperidine

  Serious - Use Alternative (1)cimetidine increases effects of meperidine by decreasing metabolism. Avoid or Use Alternate Drug.

• mestranol

  Serious - Use Alternative (1)cimetidine will increase the level or effect of mestranol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• metformin

  Monitor Closely (1)cimetidine will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• methadone

  Serious - Use Alternative (2)cimetidine will increase the level or effect of methadone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  cimetidine increases effects of methadone by decreasing metabolism. Avoid or Use Alternate Drug.

• methamphetamine

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

• methylphenidate

  Monitor Closely (1)cimetidine decreases effects of methylphenidate by enhancing GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Since the characteristics of methylphenidate extended release capsules (Ritalin LA) are pH dependent, coadministration of antacids or acid suppressants could alter the release of methylphenidate. Consider separating the administration of the antacid and the methylphenidate extended-release capsules may be avoided.

• metoprolol

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

• mexiletine

  Monitor Closely (2)cimetidine will increase the level or effect of mexiletine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of mexiletine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• midazolam

  Serious - Use Alternative (1)cimetidine will increase the level or effect of midazolam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• midazolam intranasal

  Monitor Closely (1)cimetidine 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)cimetidine will increase the level or effect of midodrine by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• mizolastine

  Monitor Closely (1)cimetidine increases levels of mizolastine by decreasing metabolism. Use Caution/Monitor.

• modafinil

  Minor (1)modafinil will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• morphine

  Monitor Closely (1)cimetidine will increase the level or effect of morphine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine increases effects of morphine by decreasing metabolism. Avoid or Use Alternate Drug.

• nalbuphine

  Serious - Use Alternative (1)cimetidine increases effects of nalbuphine by decreasing metabolism. Avoid or Use Alternate Drug.

• nateglinide

  Monitor Closely (1)cimetidine will increase the level or effect of nateglinide by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

• nebivolol

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

• nelfinavir

  Monitor Closely (1)cimetidine will increase the level or effect of nelfinavir by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will increase the level or effect of nelfinavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• neratinib

  Serious - Use Alternative (1)cimetidine will decrease the level or effect of neratinib by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• nicardipine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of nicardipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• nicotine inhaled

  Monitor Closely (1)cimetidine increases levels of nicotine inhaled by decreasing renal clearance. Use Caution/Monitor.

• nicotine intranasal

  Monitor Closely (2)cimetidine increases levels of nicotine intranasal by decreasing metabolism. Use Caution/Monitor.
  
  cimetidine increases levels of nicotine intranasal by decreasing renal clearance. Use Caution/Monitor.

• nifedipine

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

• nilotinib

  Monitor Closely (1)cimetidine decreases levels of nilotinib by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Avoid this interaction by administering H2 antagonists 10 hr after or 2 hr before nilotinib.Serious - Use Alternative (1)cimetidine will increase the level or effect of nilotinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• nimodipine

  Monitor Closely (1)cimetidine will increase the level or effect of nimodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will increase the level or effect of nimodipine by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• nisoldipine

  Serious - Use Alternative (2)cimetidine will increase the level or effect of nisoldipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  cimetidine will increase the level or effect of nisoldipine by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• nortriptyline

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

• olanzapine

  Monitor Closely (1)cimetidine will increase the level or effect of olanzapine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• olaparib

  Serious - Use Alternative (1)cimetidine will increase the level or effect of olaparib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with moderate CYP3A inhibitors cannot be avoided, reduce olaparib dose to 200 mg (capsule) or 150 mg (tablet) PO BID. Do not substitute tablets with capsules.

• oliceridine

  Monitor Closely (1)cimetidine will increase the level or effect of oliceridine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal.

• opium tincture

  Serious - Use Alternative (1)cimetidine increases effects of opium tincture by decreasing metabolism. Avoid or Use Alternate Drug.

• ospemifene

  Minor (1)cimetidine increases levels of ospemifene by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• oxcarbazepine

  Minor (1)oxcarbazepine will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• oxybutynin

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

• oxycodone

  Monitor Closely (1)cimetidine will increase the level or effect of oxycodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine increases effects of oxycodone by decreasing metabolism. Avoid or Use Alternate Drug.

• oxymorphone

  Monitor Closely (1)cimetidine will increase the level or effect of oxymorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine increases effects of oxymorphone by decreasing metabolism. Avoid or Use Alternate Drug.

• paclitaxel

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

• paclitaxel protein bound

  Monitor Closely (1)cimetidine will increase the level or effect of paclitaxel protein bound by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• palbociclib

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

• papaveretum

  Serious - Use Alternative (1)cimetidine increases effects of papaveretum by decreasing metabolism. Avoid or Use Alternate Drug.

• parecoxib

  Monitor Closely (2)cimetidine will increase the level or effect of parecoxib by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of parecoxib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)parecoxib will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• paroxetine

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

• pazopanib

  Serious - Use Alternative (1)cimetidine will decrease the level or effect of pazopanib by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Avoid coadministration of pazopanib with drugs that raise gastric pH; consider short-acting antacids in place of PPIs and H2 antagonists; separate antacid and pazopanib dosing by several hours

• pefloxacin

  Minor (1)cimetidine increases levels of pefloxacin by decreasing metabolism. Minor/Significance Unknown.

• pentazocine

  Serious - Use Alternative (1)cimetidine increases effects of pentazocine by decreasing metabolism. Avoid or Use Alternate Drug.

• pentobarbital

  Minor (1)pentobarbital will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• pentoxifylline

  Monitor Closely (1)cimetidine will increase the level or effect of pentoxifylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• perhexiline

  Minor (1)cimetidine will increase the level or effect of perhexiline by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• perphenazine

  Minor (1)cimetidine will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• pexidartinib

  Serious - Use Alternative (1)cimetidine will increase the level or effect of pexidartinib by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate pexidartinib by 2 hr before or 10 hr after taking an H2-antagonist.

• phenobarbital

  Minor (1)phenobarbital will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• phenytoin

  Monitor Closely (1)cimetidine will increase the level or effect of phenytoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

• phytoestrogens

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

• pimozide

  Contraindicated (1)cimetidine increases levels of pimozide by decreasing metabolism. Contraindicated. Risk of QT interval prolongation.Monitor Closely (1)cimetidine will increase the level or effect of pimozide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• pioglitazone

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

• pirfenidone

  Serious - Use Alternative (1)cimetidine will increase the level or effect of pirfenidone by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug. Avoid; coadministration of pirfenidone and moderate CYP1A2 inhibitors result in moderately increased exposure to pirfenidone; if unable to avoid, decrease dose of moderate CYP1A2 inhibitor

• piroxicam

  Minor (1)cimetidine will increase the level or effect of piroxicam by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• polysaccharide iron

  Monitor Closely (1)cimetidine will decrease the level or effect of polysaccharide iron by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• ponatinib

  Monitor Closely (2)ponatinib increases levels of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
  
  ponatinib increases levels of cimetidine by Other (see comment). Use Caution/Monitor.Serious - Use Alternative (1)cimetidine decreases levels of ponatinib by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• posaconazole

  Monitor Closely (1)cimetidine will decrease the level or effect of posaconazole by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• pramipexole

  Monitor Closely (1)cimetidine will increase the level or effect of pramipexole by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• praziquantel

  Monitor Closely (1)cimetidine increases levels of praziquantel by decreasing metabolism. Use Caution/Monitor.

• prednisone

  Serious - Use Alternative (1)cimetidine will increase the level or effect of prednisone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• primidone

  Minor (1)primidone will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• procainamide

  Serious - Use Alternative (1)cimetidine will increase the level or effect of procainamide by basic (cationic) drug competition for renal tubular clearance. Avoid or Use Alternate Drug.

• prochlorperazine

  Minor (1)cimetidine will increase the level or effect of prochlorperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• promazine

  Minor (1)cimetidine will increase the level or effect of promazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• promethazine

  Minor (1)cimetidine will increase the level or effect of promethazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• propafenone

  Monitor Closely (2)cimetidine will increase the level or effect of propafenone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of propafenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• propranolol

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

• quetiapine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of quetiapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• quinidine

  Serious - Use Alternative (2)cimetidine will increase the level or effect of quinidine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  quinidine will increase the level or effect of cimetidine by basic (cationic) drug competition for renal tubular clearance. Avoid or Use Alternate Drug.

• quinine

  Monitor Closely (2)cimetidine will increase the level or effect of quinine by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of quinine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• rabeprazole

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

• ramelteon

  Monitor Closely (2)cimetidine will increase the level or effect of ramelteon by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of ramelteon by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)cimetidine will increase the level or effect of ramelteon by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• ranolazine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of ranolazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rasagiline

  Monitor Closely (1)cimetidine will increase the level or effect of rasagiline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. Recommended dose of rasagiline is 0.5mg daily in combination with CYP1A2 inhibitors.

• regorafenib

  Monitor Closely (1)regorafenib will increase the level or effect of cimetidine by Other (see comment). Modify Therapy/Monitor Closely. Regorafenib likely inhibits BCRP (ABCG2) transport. Coadministration with a BCRP substrate may increase systemic exposure to the substrate and related toxicity.

• repaglinide

  Serious - Use Alternative (1)cimetidine will increase the level or effect of repaglinide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rifampin

  Minor (1)rifampin will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• rilpivirine

  Monitor Closely (1)cimetidine will decrease the level or effect of rilpivirine by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Concurrent use, may cause treatment failure and/or the development of rilpivirine or NNRTI resistance owing to decreased levels. Administer H2 antagonists at least 12 hours before or at least 4 hours after rilpivirine.

• riluzole

  Minor (1)cimetidine will increase the level or effect of riluzole by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• risedronate

  Serious - Use Alternative (1)cimetidine will increase the level or effect of risedronate by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Applies only to delayed release formulation; accelerates pH-sensitive dissolution of delayed release risedronate

• risperidone

  Minor (1)cimetidine will increase the level or effect of risperidone by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• ritonavir

  Serious - Use Alternative (1)cimetidine will increase the level or effect of ritonavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• roflumilast

  Monitor Closely (1)cimetidine increases levels of roflumilast by Other (see comment). Modify Therapy/Monitor Closely. Comment: Coadministration with dual inhibitors of CYP3A4 and CYP1A2 may increase systemic exposure and result in increased adverse reactions.

• romidepsin

  Serious - Use Alternative (1)cimetidine will increase the level or effect of romidepsin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• ropinirole

  Monitor Closely (1)cimetidine will increase the level or effect of ropinirole by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• rose hips

  Monitor Closely (1)cimetidine will decrease the level or effect of rose hips by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.

• ruxolitinib

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

• safinamide

  Monitor Closely (1)safinamide will increase the level or effect of cimetidine by Other (see comment). Use Caution/Monitor. Safinamide and its major metabolite may inhibit intestinal BCRP. Monitor BCRP substrates for increased pharmacologic or adverse effects.

• saquinavir

  Serious - Use Alternative (1)cimetidine will increase the level or effect of saquinavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• sarecycline

  Monitor Closely (1)sarecycline will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Monitor for toxicities of P-gp substrates that may require dosage reduction when coadministered with P-gp inhibitors.

• saxagliptin

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

• secobarbital

  Minor (1)secobarbital will decrease the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

• secretin

  Serious - Use Alternative (1)cimetidine, secretin. Other (see comment). Avoid or Use Alternate Drug. Comment: Concomitant use of H2-receptor antagonists may cause a hyperresponse in gastrin secretion in response to stimulation testing with secretin, falsely suggesting gastrinoma. Discontinue H2-receptor antagonists at least 2 days before administering secretin to aid in the diagnosis of gastrinoma.

• sildenafil

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

• silodosin

  Serious - Use Alternative (1)cimetidine will increase the level or effect of silodosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• simvastatin

  Serious - Use Alternative (1)cimetidine will increase the level or effect of simvastatin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• sirolimus

  Serious - Use Alternative (1)cimetidine will increase the level or effect of sirolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• sofosbuvir/velpatasvir

  Monitor Closely (2)sofosbuvir/velpatasvir will increase the level or effect of cimetidine by Other (see comment). Use Caution/Monitor. Velpatasvir is an inhibitor of the drug transporter BCRP. Coadministration may increase systemic exposure of drugs that are BCRP substrates.
  
  cimetidine will decrease the level or effect of sofosbuvir/velpatasvir by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Velpatasvir solubility decreases as gastric pH increases (practically insoluble at pH >5). H2 receptor antagonists may be administered simultaneously with or 12 hr apart from sofosbuvir/velpatasvir at a dose that does not exceed doses comparable to famotidine 40 mg BID.

• solifenacin

  Serious - Use Alternative (1)cimetidine will increase the level or effect of solifenacin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• sonidegib

  Monitor Closely (1)cimetidine will increase the level or effect of sonidegib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid coadministration of sonidegib with moderate CYP3A4 inhibitors. If a moderate CYP3A inhibitor must be used, administer the moderate CYP3A inhibitor for <14 days and monitor closely for adverse reactions, particularly musculoskeletal adverse reactions.

• sotorasib

  Serious - Use Alternative (2)cimetidine will decrease the level or effect of sotorasib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If use with an acid-reducing agent cannot be avoided, administer sotorasib 4 hr before or 10 hr after administration of a locally-acting antacid.
  
  sotorasib will decrease the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If use is unavoidable, refer to the prescribing information of the P-gp substrate for dosage modifications.

• stiripentol

  Monitor Closely (2)stiripentol will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Consider reducing the dose of P-glycoprotein (P-gp) substrates, if adverse reactions are experienced when administered concomitantly with stiripentol.
  
  stiripentol will increase the level or effect of cimetidine by Other (see comment). Modify Therapy/Monitor Closely. Stiripentol is a BCRP transport inhibitor. Consider dosage reduction for BCRP substrates if adverse effects are experienced when coadministered.

• sufentanil

  Monitor Closely (1)cimetidine will increase the level or effect of sufentanil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine increases effects of sufentanil by decreasing metabolism. Avoid or Use Alternate Drug.

• sulfamethoxazole

  Monitor Closely (1)cimetidine will increase the level or effect of sulfamethoxazole by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.Minor (1)cimetidine will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• sunitinib

  Serious - Use Alternative (1)cimetidine will increase the level or effect of sunitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• suvorexant

  Monitor Closely (1)cimetidine will increase the level or effect of suvorexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease suvorexant starting dose to 5 mg HS if coadministered with moderate CYP3A4 inhibitors

• tacrolimus

  Serious - Use Alternative (1)cimetidine will increase the level or effect of tacrolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• tadalafil

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

• tafamidis

  Monitor Closely (1)tafamidis will increase the level or effect of cimetidine by Other (see comment). Use Caution/Monitor. Tafamidis inhibits breast cancer resistant protein (BCRP) in vitro and may increase exposure of BCRP substrates following tafamidis or tafamidis meglumine administration. Dosage adjustment of these BCRP substrates may be necessary.

• tafamidis meglumine

  Monitor Closely (1)tafamidis meglumine will increase the level or effect of cimetidine by Other (see comment). Use Caution/Monitor. Tafamidis inhibits breast cancer resistant protein (BCRP) in vitro and may increase exposure of BCRP substrates following tafamidis or tafamidis meglumine administration. Dosage adjustment of these BCRP substrates may be necessary.

• tafenoquine

  Serious - Use Alternative (1)tafenoquine will increase the level or effect of cimetidine by Other (see comment). Avoid or Use Alternate Drug. Tafenoquine inhibits organic cation transporter-2 (OCT2) and multidrug and toxin extrusion (MATE) transporters in vitro. Avoid coadministration with OCT2 or MATE substrates. If coadministration cannot be avoided, monitor for substrate-related toxicities and consider dosage reduction if needed based on product labeling of the coadministered drug.

• tamoxifen

  Monitor Closely (1)cimetidine, tamoxifen. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibition decreases metabolism of tamoxifen to N-desmethyl tamoxifen (active metabolite with similar biologic activity).

• tamsulosin

  Monitor Closely (2)cimetidine increases levels of tamsulosin by decreasing renal clearance. Use Caution/Monitor. Decreases tamsulosin clearance by 26% resulting in increased AUC (44%).
  
  cimetidine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• tapentadol

  Serious - Use Alternative (1)cimetidine increases effects of tapentadol by decreasing metabolism. Avoid or Use Alternate Drug.

• tazemetostat

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

• temsirolimus

  Serious - Use Alternative (1)cimetidine will increase the level or effect of temsirolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• tenofovir DF

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

• tepotinib

  Serious - Use Alternative (1)tepotinib will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If concomitant use unavoidable, reduce the P-gp substrate dosage if recommended in its approved product labeling.

• tetanus toxoid adsorbed or fluid

  Monitor Closely (1)cimetidine increases levels of tetanus toxoid adsorbed or fluid by decreasing metabolism. Use Caution/Monitor.

• theophylline

  Monitor Closely (1)cimetidine will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• thioridazine

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

• timolol

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

• tinidazole

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

• tipranavir

  Serious - Use Alternative (1)cimetidine will increase the level or effect of tipranavir by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• tizanidine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of tizanidine by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug.

• tofacitinib

  Monitor Closely (2)cimetidine increases levels of tofacitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No specific dose adjustment recommended when tofacitinib coadministered with moderate CYP3A4 inhibitors; decrease tofacitinib dose if coadministered with both moderate CYP3A4 and potent CYP2C19 inhibitors.
  
  cimetidine increases levels of tofacitinib by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. No specific dose adjustment recommended when tofacitinib coadministered with potent CYP2C19 inhibitors; decrease tofacitinib dose if coadministered with both moderate CYP3A4 and potent CYP2C19 inhibitors .Serious - Use Alternative (1)cimetidine increases levels of tofacitinib by decreasing metabolism. Avoid or Use Alternate Drug. Reduce tofacitinib dose to 5 mg qDay when coadministered with 1 or more concomitant medications that result in both moderate CYP3A4 inhibition and potent CYP2C19 inhibition.

• tolbutamide

  Monitor Closely (1)cimetidine will increase the level or effect of tolbutamide by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor.Minor (1)cimetidine will increase the level or effect of tolbutamide by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• tolterodine

  Serious - Use Alternative (1)cimetidine will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)cimetidine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• tolvaptan

  Serious - Use Alternative (1)cimetidine will increase the level or effect of tolvaptan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• tramadol

  Monitor Closely (2)cimetidine decreases effects of tramadol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Decreased conversion of tramadol to active metabolite.
  
  cimetidine decreases effects of tramadol by decreasing metabolism. Use Caution/Monitor. Decreased conversion of tramadol to active metabolite.

• trazodone

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

• triamcinolone acetonide injectable suspension

  Serious - Use Alternative (1)cimetidine will increase the level or effect of triamcinolone acetonide injectable suspension by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• triamterene

  Monitor Closely (1)cimetidine will increase the level or effect of triamterene by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• triazolam

  Serious - Use Alternative (1)cimetidine will increase the level or effect of triazolam by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• trifluoperazine

  Minor (1)cimetidine will increase the level or effect of trifluoperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• trilaciclib

  Serious - Use Alternative (1)trilaciclib will decrease the level or effect of cimetidine by Other (see comment). Avoid or Use Alternate Drug. Avoid coadministration of trilaciclib (OCT2, MATE1, and MATE-2K inhibitor) with substrates where minimal increased concentration in kidney or blood may lead to serious or life-threatening toxicities.

• trimethoprim

  Monitor Closely (1)cimetidine will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

• tropisetron

  Minor (1)cimetidine will increase the level or effect of tropisetron by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• tucatinib

  Monitor Closely (1)tucatinib will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Consider reducing the dosage of P-gp substrates, where minimal concentration changes may lead to serious or life-threatening toxicities.

• valacyclovir

  Monitor Closely (1)cimetidine increases levels of valacyclovir by decreasing renal clearance. Use Caution/Monitor.

• vandetanib

  Monitor Closely (1)vandetanib increases levels of cimetidine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Vandetanib inhibits the uptake of substrates of organic cation transporter type 2 (OCT2).

• vardenafil

  Serious - Use Alternative (1)cimetidine will increase the level or effect of vardenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• varenicline

  Minor (1)cimetidine increases levels of varenicline by decreasing renal clearance. Minor/Significance Unknown.

• verapamil

  Monitor Closely (1)cimetidine will increase the level or effect of verapamil by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will increase the level or effect of verapamil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• vilazodone

  Serious - Use Alternative (1)cimetidine increases levels of vilazodone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If intolerable adverse effects occur when coadministered with moderate CYP3A4 inhibitors, reduce daily dose to 20 mg.

• vinblastine

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

• vincristine

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

• vincristine liposomal

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

• vinorelbine

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

• vismodegib

  Monitor Closely (1)cimetidine will decrease the level or effect of vismodegib by Other (see comment). Use Caution/Monitor. Drugs that increase gastric pH alter vismodegib solubility and therefore reduce bioavailability; effect on efficacy unknown

• voriconazole

  Minor (2)voriconazole will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.
  
  cimetidine will increase the level or effect of voriconazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

• warfarin

  Monitor Closely (2)cimetidine will increase the level or effect of warfarin by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
  
  cimetidine will increase the level or effect of warfarin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will increase the level or effect of warfarin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• zaleplon

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

• ziprasidone

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

• zolmitriptan

  Monitor Closely (1)cimetidine increases levels of zolmitriptan by unknown mechanism. Modify Therapy/Monitor Closely. Half-life and blood levels of zolmitriptan and its active N-desmethyl metabolite are approximately doubled when coadministered with cimetidine; limit zolmitriptan to 2.5 mg/dose and 5 mg/day.

• zolpidem

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

• zonisamide

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