Duodenal ulcer, treatment and maintenance:
Children ≥5 years and Adolescents <16 years: Limited data available, efficacy results variable: Oral: 20 to 40 mg/kg/day in 3 to 4 divided doses for 4 to 8 weeks (maximum dose: 300 mg/dose), followed by 5 to 8 mg/kg/dose once daily at bedtime (maximum dose: 400 mg/dose) (Ref).
Adolescents ≥16 years: Oral: 800 mg at bedtime or 400 mg twice daily or 300 mg 4 times daily for up to 8 weeks, followed by maintenance therapy of 400 mg once daily at bedtime (Ref). Note: Although treatment of active duodenal ulcers and maintenance therapy are included in the FDA manufacturer's labeling, use has fallen out of favor and in adults, experts suggest that cimetidine not be routinely used due to several cimetidine drug interactions and the preference for other options (eg, other histamine H2 antagonists, proton pump inhibitors [PPIs]).
Gastric ulcer, active: Adolescents ≥16 years: Oral: 800 mg at bedtime or 300 mg 4 times daily for up to 8 weeks (Ref). Note: Although treatment of active gastric ulcers is included in the FDA manufacturer's labeling, use has fallen out of favor and in adults, experts suggest that cimetidine not be routinely used due to several cimetidine drug interactions and the preference for other options (eg, other histamine H2 antagonists, PPIs).
Gastroesophageal reflux disease (GERD):
Infants, Children, and Adolescents <16 years: Limited data available: Oral: 30 to 40 mg/kg/day in 4 divided doses; maximum dose: 400 mg/dose (Ref). A pharmacokinetic modeling study suggests that the optimal dose for acid suppression is 10 mg/kg/dose every 6 hours and that some patients may need doses as high as 15 mg/kg/dose (Ref).
Adolescents ≥16 years: Oral: 400 mg 4 times daily or 800 mg twice daily for 12 weeks (Ref).
Pathological hypersecretory conditions (eg, Zollinger-Ellison syndrome, systemic mastocytosis, multiple endocrine adenomas):
Adolescents ≥16 years: Oral: 300 mg 4 times daily; adjust dose to patient response; maximum daily dose: 2,400 mg/day (Ref). Note: Although treatment of pathological hypersecretory conditions is included in the FDA manufacturer's labeling, use has fallen out of favor and in adults, experts suggest that cimetidine not be routinely used due to several cimetidine drug interactions and the preference for other options (eg, other histamine H2 antagonists, PPIs).
Sour stomach/Heartburn (OTC labeling):
Prevention: Children ≥12 years and Adolescents: Oral: 200 mg daily up to 30 minutes prior to eating foods or beverages that cause heartburn (maximum daily dose: 400 mg/24 hours).
Relief of symptoms: Children ≥12 years and Adolescents: Oral: 200 mg daily; maximum daily dose: 400 mg/24 hours.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Adolescents ≥16 years: Oral (Ref):
Mild to moderate renal impairment: There are no dosage adjustments provided in the manufacturer’s labeling; use with caution.
Severe renal impairment: 300 mg every 12 hours; may increase frequency with caution. When hepatic impairment is also present, further reductions in dosage may be necessary.
Adolescents ≥16 years: There are no dosage adjustments provided in the manufacturer’s labeling; use with caution. Dosage adjustments may be needed in patients with both renal and hepatic impairment.
(For additional information see "Cimetidine: Drug information")
Erosive esophagitis due to gastroesophageal reflux disease (alternative agent):
Note: Although a labeled indication, H2-receptor antagonists (eg, cimetidine) for the treatment of erosive esophagitis due to gastroesophageal reflux disease are not preferred due to the availability of proton pump inhibitors (Ref).
Oral: 400 mg 4 times daily or 800 mg twice daily for 12 weeks.
Heartburn (OTC labeling):
Prevention: Oral: 200 mg daily up to 30 minutes prior to eating foods or beverages that cause heartburn (maximum: 400 mg per 24 hours).
Relief of symptoms: Oral: 200 mg daily; maximum: 400 mg per 24 hours.
Interstitial cystitis (bladder pain syndrome) (off-label use): Oral: 200 mg 3 times daily or 300 to 400 mg twice daily (Ref).
Pathological hypersecretory conditions (eg, Zollinger-Ellison syndrome [gastrinoma]) (alternative agent):
Note: Although a labeled indication, clinical experience suggests that H2-receptor antagonists (eg, cimetidine) are not preferred for controlling acid hypersecretion in pathological hypersecretory conditions (eg, Zollinger-Ellison syndrome) due to the availability of proton pump inhibitors (Ref).
Oral: 300 mg 4 times daily; adjust dose to patient response; maximum 2.4 g/day.
Peptic ulcer disease (duodenal or benign gastric ulcers) (alternative agent):
Note: Although a labeled indication, current guidelines recommend proton pump inhibitors as standard of care for treatment of peptic ulcer disease rather than H2-receptor antagonists (eg, cimetidine) (Ref).
Duodenal ulcer, active: Oral: 300 mg 4 times daily, or 400 mg twice daily, or 800 mg once daily at bedtime for up to 8 weeks.
Note: Higher doses of 1.6 g once daily at bedtime for 4 weeks may be beneficial for patients with duodenal ulcers >1 cm (defined endoscopically) who smoke ≥1 pack/day.
Duodenal ulcer, prophylaxis: Oral: 400 mg once daily at bedtime.
Gastric ulcer, active: Oral: 300 mg 4 times daily or 800 mg once daily at bedtime for up to 8 weeks.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Manufacturer's labeling:
Mild to moderate kidney impairment: There are no dosage adjustments provided in the manufacturer’s labeling; use with caution.
Severe kidney impairment: 300 mg every 12 hours; may increase frequency with caution. When hepatic impairment is also present, further reductions in dosage may be necessary.
Alternate recommendations (Ref):
GFR >50 mL/minute: No dosage adjustment necessary.
GFR 10 to 50 mL/minute: Administer 50% of normal dose.
GFR <10 mL/minute: 300 mg every 8 to 12 hours.
Hemodialysis: Dose after dialysis.
CRRT: Administer 50% of normal dose.
Peritoneal dialysis: 300 mg every 8 to 12 hours.
Geriatric patients ≥65 years: CrCl <50 mL/minute: Reduce the dose because of risk of mental status changes (specific dosage adjustment is not provided (Ref).
Stress ulcer prophylaxis in critically ill patients (off-label use): CrCl <30 mL/minute: 300 mg twice daily (Ref).
There are no dosage adjustments provided in the manufacturer’s labeling; use with caution. Dosage adjustments may be needed in patients with both kidney and hepatic impairment.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
1% to 10%:
Central nervous system: Headache (2% to 4%), dizziness (1%), drowsiness (1%)
Endocrine & metabolic: Gynecomastia (≤4%)
Gastrointestinal: Diarrhea (1%)
Frequency not defined: Renal: Increased serum creatinine
Postmarketing: Agitation, agranulocytosis, alopecia, anaphylaxis, anxiety, aplastic anemia, arthralgia, confusion, decreased white blood cell count, depression, disorientation, fever (Potter 1986), hallucination, hemolytic anemia (immune-based), hepatic fibrosis, hypersensitivity angiitis, hypersensitivity reaction, hypotension, impotence (Jensen 1983), increased serum transaminases, interstitial nephritis, myalgia, pancreatitis, pancytopenia, polymyositis (Watson 1983), psychosis, urinary retention, thrombocytopenia
Hypersensitivity to cimetidine or any component of the formulation
OTC labeling: When used for self-medication (OTC), do not use if trouble or pain when swallowing food, vomiting with blood, or bloody or black stools, allergic to cimetidine or other acid reducers. Do not use with other acid reducers.
Concerns related to adverse effects:
• Confusion: Rare cases of reversible confusion have been associated with cimetidine; usually in older or severely ill patients, or in patients with kidney or hepatic impairment.
• Vitamin B12 deficiency: Prolonged treatment (≥2 years) may lead to vitamin B12 malabsorption and subsequent vitamin B12 deficiency. The magnitude of the deficiency is dose-related and the association is stronger in females and those younger in age (<30 years); prevalence is decreased after discontinuation of therapy (Lam 2013).
Disease-related concerns:
• Gastric malignancy: Relief of symptoms does not preclude the presence of a gastric malignancy.
• Hepatic impairment: Use with caution in patients with hepatic impairment.
• Kidney impairment: Use with caution in patients with kidney impairment; dosage adjustment recommended.
Special populations:
• Immunocompromised patients: May have increased risk of hyperinfection of strongyloidiasis.
• Older adults: Use caution in this age group due to risk of confusion and other CNS effects. Cimetidine should be avoided in those older adults with, or at risk of, delirium.
Other warnings/precautions:
• Serum creatinine/creatinine clearance estimates: Cimetidine can cause a transient and reversible rise in serum creatinine and/or decrease in CrCl (when using routine CrCl estimation formulas). This interference is likely due to competitive inhibition of cimetidine with creatinine for active tubular secretion and independent of an actual change in GFR. In patients with normal kidney function, the rise in serum creatinine may not be clinically apparent, but in patients with varying degrees of kidney impairment, this rise in serum creatinine may be more significant. Thus, treatment with cimetidine in patients with kidney failure may invalidate measurements of serum creatinine and estimates of CrCl (Andreev 1999; Larsson 1980). However, CrCl estimation formulas, such as Cockcroft-Gault, are known to overestimate actual GFR, particularly in patients with kidney impairment, and use of cimetidine has been explored clinically to improve the accuracy of CrCl estimates in these patients (Choi 1993; Van Acker 1992).
• OTC labeling: When used for self-medication (OTC), notify health care provider before use if any of the following are present: frequent chest pain; frequent wheezing particularly with heartburn; nausea/vomiting; unexplained weight loss; stomach pain; heartburn >3 months; heartburn with light-headedness, sweating, or dizziness; chest pain or shoulder pain with shortness of breath; sweating or pain that spreads to arms, neck, or shoulders; light-headedness. Stop use and notify health care provider if heartburn continues or worsens, stomach pain continues, or if use is required >14 days.
Use of gastric acid inhibitors, including proton pump inhibitors and H2 blockers, has been associated with an increased risk for development of acute gastroenteritis and community-acquired pneumonia in pediatric patients (Canani 2006). A large epidemiological study has suggested an increased risk for developing pneumonia in patients receiving H2 receptor antagonists; however, a causal relationship with cimetidine has not been demonstrated. A cohort analysis including more than 11,000 neonates reported an association between H2 blocker use and an increased incidence of necrotizing enterocolitis (NEC) in very low birth weight (VLBW) neonates (Guillet 2006). An approximate sixfold increase in mortality, NEC, and infection (ie, sepsis, pneumonia, urinary tract infection) was reported in patients receiving another H2 blocker, ranitidine, in a cohort analysis of 274 VLBW neonates (Terrin 2012).
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Solution, Oral, as hydrochloride [strength expressed as base]:
Generic: 400 mg/6.67 mL (6.67 mL [DSC]); 300 mg/5 mL (5 mL, 237 mL)
Tablet, Oral:
Cimetidine Acid Reducer: 200 mg
Generic: 200 mg, 300 mg, 400 mg, 800 mg
Yes
Solution (Cimetidine HCl Oral)
300 mg/5 mL (per mL): $22.93
Tablets (Cimetidine Oral)
200 mg (per each): $1.55
300 mg (per each): $1.61 - $2.05
400 mg (per each): $2.61 - $3.34
800 mg (per each): $5.02 - $6.20
Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Tablet, Oral:
Generic: 200 mg, 300 mg, 600 mg [DSC], 800 mg
Note: Commercial oral solution is available (strength expressed as base: 60 mg/mL).
60 mg/mL oral suspension
A 60 mg/mL oral suspension may be made with tablets. Place twenty-four 300 mg tablets in 5 mL of sterile water for ~3 to 5 minutes to dissolve film coating. Crush tablets in a mortar and reduce to a fine powder. Add 10 mL of glycerin and mix to a uniform paste; mix while adding Simple Syrup, NF in incremental proportions to almost 120 mL; transfer to a calibrated bottle, rinse mortar with vehicle, and add quantity of vehicle sufficient to make 120 mL. Label "shake well" and "refrigerate." Stable for 17 days.
Oral: Administer with food; do not administer simultaneously with antacids.
Oral: Administer with meals. For stress ulcer prophylaxis in critically-ill patients (off-label use), may administer via NG tube (Ref).
Store at room temperature. Protect from light.
Short-term and maintenance treatment of duodenal ulcers; short-term treatment of active benign gastric ulcers; treatment of gastroesophageal reflux disease (GERD); treatment of pathologic hypersecretory conditions (eg, Zollinger-Ellison syndrome, systemic mastocytosis, multiple endocrine adenomas) (All indications: FDA approved in ages ≥16 years and adults); relief and prevention of heartburn associated with acid indigestion and sour stomach (OTC product: FDA approved in ages ≥12 years and adults).
Note: Although duodenal and gastric ulcer treatment and treatment of pathological hypersecretory conditions are included in the FDA manufacturer's labeling, use has fallen out of favor and in adults, experts suggest that cimetidine not be routinely used due to several cimetidine drug interactions and the preference for other options (eg, other histamine H2 antagonists, proton pump inhibitors [PPIs]).
Cimetidine may be confused with simethicone
Substrate of MATE1/2-K, OAT1/3, P-glycoprotein (Minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential; Inhibits CYP1A2 (Weak), CYP2C19 (Weak), CYP2D6 (Weak), CYP3A4 (Weak), MATE1/2-K, OCT1, OCT2;
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program
Acalabrutinib: Histamine H2 Receptor Antagonists may decrease serum concentration of Acalabrutinib. Management: Give acalabrutinib capsules 2 hours before a histamine H2 receptor antagonist (H2RA). No action is required if acalabrutinib tablets are coadministered with H2RAs. Risk D: Consider Therapy Modification
ALfentanil: Cimetidine may increase serum concentration of ALfentanil. Risk C: Monitor
ALPRAZolam: CYP3A4 Inhibitors (Weak) may increase serum concentration of ALPRAZolam. Risk C: Monitor
Amiodarone: Cimetidine may increase serum concentration of Amiodarone. Risk X: Avoid
Atazanavir: Histamine H2 Receptor Antagonists may decrease serum concentration of Atazanavir. Management: Specific dose limitations and administration guidelines exist; consult full interaction monograph or atazanavir prescribing information. Risk D: Consider Therapy Modification
Azelastine (Systemic): Cimetidine may increase serum concentration of Azelastine (Systemic). Risk C: Monitor
Belumosudil: Histamine H2 Receptor Antagonists may decrease serum concentration of Belumosudil. Risk C: Monitor
Bosutinib: Histamine H2 Receptor Antagonists may decrease serum concentration of Bosutinib. Management: Administer histamine H2 receptor antagonists (H2RAs) more than 2 hours before or after bosutinib. Risk D: Consider Therapy Modification
Bromazepam: Cimetidine may increase serum concentration of Bromazepam. Risk C: Monitor
Calcium Channel Blockers: Cimetidine may increase serum concentration of Calcium Channel Blockers. Risk C: Monitor
CarBAMazepine: CYP3A4 Inhibitors (Weak) may increase serum concentration of CarBAMazepine. Risk C: Monitor
Carmustine: Cimetidine may increase myelosuppressive effects of Carmustine. Management: Consider alternatives to cimetidine in patients receiving carmustine. If the combination cannot be avoided, monitor for enhanced carmustine myelotoxicity. Risk D: Consider Therapy Modification
Cefditoren: Histamine H2 Receptor Antagonists may decrease serum concentration of Cefditoren. Risk X: Avoid
Cefpodoxime: Histamine H2 Receptor Antagonists may decrease serum concentration of Cefpodoxime. Risk C: Monitor
Cefuroxime: Histamine H2 Receptor Antagonists may decrease absorption of Cefuroxime. Management: Avoid concomitant use of oral cefuroxime axetil and H2 receptor antagonists if possible. If combined, ensure oral cefuroxime axetil is taken with food to minimize the magnitude of this interaction. Risk D: Consider Therapy Modification
ChlordiazePOXIDE: Cimetidine may increase serum concentration of ChlordiazePOXIDE. Risk C: Monitor
Chlormethiazole: Cimetidine may increase serum concentration of Chlormethiazole. Risk C: Monitor
Chloroquine: Cimetidine may increase serum concentration of Chloroquine. Risk X: Avoid
Cisapride: Cimetidine may increase serum concentration of Cisapride. Management: Consider alternatives to cimetidine. If this combination cannot be avoided, monitor for toxic effects of cisapride, particularly QTc interval prolongation. Risk D: Consider Therapy Modification
Citalopram: Cimetidine may increase serum concentration of Citalopram. Management: Limit citalopram dose to a maximum of 20 mg/day if used with cimetidine. Patients using this combination should be monitored closely for evidence of citalopram toxicity (eg, serotonin syndrome, QT prolongation). Risk D: Consider Therapy Modification
CloBAZam: CYP2C19 Inhibitors (Weak) may increase serum concentration of CloBAZam. CYP2C19 Inhibitors (Weak) may increase active metabolite exposure of CloBAZam. Risk C: Monitor
Clofarabine: OCT2 Inhibitors may increase serum concentration of Clofarabine. Risk C: Monitor
CloZAPine: Cimetidine may increase serum concentration of CloZAPine. Risk C: Monitor
CycloSPORINE (Systemic): CYP3A4 Inhibitors (Weak) may increase serum concentration of CycloSPORINE (Systemic). Risk C: Monitor
Cysteamine (Systemic): Histamine H2 Receptor Antagonists may decrease therapeutic effects of Cysteamine (Systemic). Risk C: Monitor
Dacomitinib: Histamine H2 Receptor Antagonists may decrease serum concentration of Dacomitinib. Management: Administer dacomitinib at least 6 hours before or 10 hours after an histamine H2-receptor antagonist (H2RA). Risk D: Consider Therapy Modification
Dalfampridine: OCT2 Inhibitors may increase serum concentration of Dalfampridine. Management: Consider alternatives to this combination. Carefully weigh the risk of seizures against the benefit of combining OCT2 inhibitors with dalfampridine. Risk D: Consider Therapy Modification
Dasatinib: Histamine H2 Receptor Antagonists may decrease absorption of Dasatinib. Management: Do not administer H2RAs with dasatinib. Antacids (taken 2 hours before or after dasatinib) can be used in place of H2-antagonists if some acid-reducing therapy is needed. No interaction is expected with the Phyrago brand of dasatinib. Risk X: Avoid
Dofetilide: Cimetidine may increase serum concentration of Dofetilide. This is likely via inhibition of dofetilide renal tubular secretion (primarily) and inhibition of dofetilide metabolism. Risk X: Avoid
Doxofylline: Cimetidine may increase serum concentration of Doxofylline. Risk C: Monitor
EpiRUBicin: Cimetidine may increase serum concentration of EpiRUBicin. Risk X: Avoid
Erlotinib: Histamine H2 Receptor Antagonists may decrease serum concentration of Erlotinib. Management: Avoid H2-antagonists in patients receiving erlotinib when possible. If concomitant treatment cannot be avoided, erlotinib should be dosed once daily, 10 hours after and at least 2 hours before H2-antagonist dosing. Risk D: Consider Therapy Modification
Erythromycin (Systemic): Cimetidine may increase serum concentration of Erythromycin (Systemic). Risk C: Monitor
Escitalopram: Cimetidine may increase serum concentration of Escitalopram. Risk C: Monitor
Fezolinetant: CYP1A2 Inhibitors (Weak) may increase serum concentration of Fezolinetant. Risk X: Avoid
Finerenone: CYP3A4 Inhibitors (Weak) may increase serum concentration of Finerenone. Risk C: Monitor
Flibanserin: CYP3A4 Inhibitors (Weak) may increase serum concentration of Flibanserin. Risk C: Monitor
Flunitrazepam: Cimetidine may increase serum concentration of Flunitrazepam. Risk C: Monitor
Fluorouracil Products: Cimetidine may increase serum concentration of Fluorouracil Products. Risk C: Monitor
FLUoxetine: Cimetidine may increase serum concentration of FLUoxetine. Risk C: Monitor
Fosamprenavir: Histamine H2 Receptor Antagonists may decrease serum concentration of Fosamprenavir. Cimetidine may also inhibit the metabolism of the active metabolite amprenavir, making its effects on fosamprenavir/amprenavir concentrations difficult to predict. Risk C: Monitor
Fosphenytoin-Phenytoin: Cimetidine may increase adverse/toxic effects of Fosphenytoin-Phenytoin. Cimetidine may increase serum concentration of Fosphenytoin-Phenytoin. Management: Consider using an alternative H2-antagonist to avoid this interaction. Monitor for toxic effects of hydantoin antiseizure drugs if cimetidine is initiated/dose increased. Risk D: Consider Therapy Modification
Gefitinib: Histamine H2 Receptor Antagonists may decrease serum concentration of Gefitinib. Management: Administer gefitinib at least 6 hours before or 6 hours after administration of a histamine H2 receptor antagonist (H2RA), and closely monitor clinical response to gefitinib. Risk D: Consider Therapy Modification
GlipiZIDE: Cimetidine may increase serum concentration of GlipiZIDE. Risk C: Monitor
Hydroxychloroquine: Cimetidine may increase serum concentration of Hydroxychloroquine. Risk X: Avoid
Indinavir: Histamine H2 Receptor Antagonists may decrease serum concentration of Indinavir. Risk C: Monitor
Itraconazole: Histamine H2 Receptor Antagonists may increase serum concentration of Itraconazole. Histamine H2 Receptor Antagonists may decrease serum concentration of Itraconazole. Management: Administer Sporanox brand itraconazole at least 2 hours before or 2 hours after administration of any histamine H2 receptor antagonists (H2RAs). Exposure to Tolsura brand itraconazole may be increased by H2RAs; consider itraconazole dose reduction. Risk D: Consider Therapy Modification
Ixabepilone: CYP3A4 Inhibitors (Weak) may increase serum concentration of Ixabepilone. Risk C: Monitor
Ketoconazole (Systemic): Histamine H2 Receptor Antagonists may decrease serum concentration of Ketoconazole (Systemic). Management: Administer ketoconazole with an acidic beverage (eg, non-diet cola) and monitor for reduced efficacy if concomitant use with a H2RA is required. Increases in ketoconazole dose may be required. Risk D: Consider Therapy Modification
Ledipasvir: Histamine H2 Receptor Antagonists may decrease serum concentration of Ledipasvir. Management: Administer H2 receptor antagonist doses less than or comparable to famotidine 40 mg twice daily simultaneously or 12 hours prior to ledipasvir. The effect of administering H2 receptor antagonists at other time intervals is unknown and not recommended. Risk D: Consider Therapy Modification
Lemborexant: CYP3A4 Inhibitors (Weak) may increase serum concentration of Lemborexant. Management: The maximum recommended dosage of lemborexant is 5 mg, no more than once per night, when coadministered with weak CYP3A4 inhibitors. Risk D: Consider Therapy Modification
Levoketoconazole: Histamine H2 Receptor Antagonists may decrease absorption of Levoketoconazole. Risk X: Avoid
Lidocaine (Systemic): Cimetidine may increase serum concentration of Lidocaine (Systemic). Risk C: Monitor
Lidocaine (Topical): Cimetidine may increase serum concentration of Lidocaine (Topical). Risk C: Monitor
Lomitapide: CYP3A4 Inhibitors (Weak) may increase serum concentration of Lomitapide. Management: Patients on lomitapide 5 mg/day may continue that dose. Patients taking lomitapide 10 mg/day or more should decrease the lomitapide dose by half. The lomitapide dose may then be titrated up to a max adult dose of 30 mg/day. Risk D: Consider Therapy Modification
Mavacamten: CYP2C19 Inhibitors (Weak) may increase serum concentration of Mavacamten. Management: Start mavacamten at 5 mg/day if stable on a weak CYP2C19 inhibitor, and reduce the mavacamten dose by one dose level if initiating a weak CYP2C19 inhibitor. Avoid initiating weak CYP2C19 inhibitors in patients on mavacamten 2.5 mg/day. Risk D: Consider Therapy Modification
Melatonin: Cimetidine may increase serum concentration of Melatonin. Risk C: Monitor
Melperone: Cimetidine may increase serum concentration of Melperone. Risk X: Avoid
Meperidine: Cimetidine may increase serum concentration of Meperidine. Risk C: Monitor
MetFORMIN: Cimetidine may increase serum concentration of MetFORMIN. Management: Consider alternatives to cimetidine in patients receiving metformin due to a potential for increased metformin concentrations and toxicity (including lactic acidosis). Risk D: Consider Therapy Modification
Midazolam: CYP3A4 Inhibitors (Weak) may increase serum concentration of Midazolam. Risk C: Monitor
Mirtazapine: Cimetidine may increase serum concentration of Mirtazapine. Risk C: Monitor
Moclobemide: Cimetidine may increase serum concentration of Moclobemide. Management: Consider using alternative agents to increase gastric pH in order to avoid this interaction. If combined, a moclobemide dose reduction of 50% may be necessary, and patients should be monitored for increased moclobemide effects/toxicities. Risk D: Consider Therapy Modification
Nelfinavir: Histamine H2 Receptor Antagonists may decrease serum concentration of Nelfinavir. Concentrations of the active M8 metabolite may also be reduced. Histamine H2 Receptor Antagonists may decrease active metabolite exposure of Nelfinavir. Risk C: Monitor
Neratinib: Histamine H2 Receptor Antagonists may decrease serum concentration of Neratinib. Specifically, histamine H2 receptor antagonists may reduce neratinib absorption. Management: Administer neratinib at least 2 hours before or 10 hours after administration of a histamine H2 receptor antagonist to minimize the impact of this interaction. Risk D: Consider Therapy Modification
NIFEdipine (Topical): Cimetidine may increase serum concentration of NIFEdipine (Topical). Risk C: Monitor
Nilotinib: Histamine H2 Receptor Antagonists may decrease serum concentration of Nilotinib. Management: The nilotinib dose should be given 10 hours after or 2 hours before the H2 receptor antagonist in order to minimize the risk of a significant interaction. Risk D: Consider Therapy Modification
NiMODipine: CYP3A4 Inhibitors (Weak) may increase serum concentration of NiMODipine. Risk C: Monitor
Nirogacestat: Histamine H2 Receptor Antagonists may decrease serum concentration of Nirogacestat. Risk X: Avoid
Octreotide: Histamine H2 Receptor Antagonists may decrease serum concentration of Octreotide. Risk C: Monitor
Opipramol: Cimetidine may increase serum concentration of Opipramol. Management: Reduce the opipramol dose and monitor for increased opipramol adverse effects (eg, dizziness, drowsiness, tachycardia, constipation) during coadministration with cimetidine. Risk D: Consider Therapy Modification
Ornidazole: Cimetidine may increase serum concentration of Ornidazole. Risk C: Monitor
PARoxetine: Cimetidine may increase serum concentration of PARoxetine. Risk C: Monitor
PAZOPanib: Histamine H2 Receptor Antagonists may decrease serum concentration of PAZOPanib. Risk X: Avoid
Pentoxifylline: Cimetidine may increase serum concentration of Pentoxifylline. Risk C: Monitor
Pexidartinib: Histamine H2 Receptor Antagonists may decrease serum concentration of Pexidartinib. Management: Administer pexidartinib 2 hours before or 10 hours after histamine H2 receptor antagonists. Risk D: Consider Therapy Modification
Pilsicainide: Cimetidine may increase serum concentration of Pilsicainide. Risk C: Monitor
Pimozide: CYP3A4 Inhibitors (Weak) may increase serum concentration of Pimozide. Risk X: Avoid
Posaconazole: Cimetidine may decrease serum concentration of Posaconazole. Management: Avoid concurrent cimetidine unless potential benefits outweigh the risks of possible inadequate response. If concomitant use cannot be avoided, monitor steady state posaconazole trough levels and monitor for evidence of decreased antifungal effects. Risk D: Consider Therapy Modification
Pramipexole: Cimetidine may increase serum concentration of Pramipexole. Risk C: Monitor
Praziquantel: Cimetidine may increase serum concentration of Praziquantel. Risk C: Monitor
Procainamide: Cimetidine may increase serum concentration of Procainamide. Management: Consider an alternative H2-receptor antagonist in patients taking procainamide. If combined, monitor for increased therapeutic effects/toxicity of procainamide. Risk D: Consider Therapy Modification
Propranolol: Cimetidine may increase serum concentration of Propranolol. Risk C: Monitor
QuiNIDine: Cimetidine may increase serum concentration of QuiNIDine. Risk C: Monitor
QuiNINE: Cimetidine may increase serum concentration of QuiNINE. Management: Consider using an alternative H2-receptor antagonist (eg, ranitidine) instead of cimetidine due to a lower interaction risk. If combined, monitor patients closely for signs and symptoms of quinine toxicity. Risk D: Consider Therapy Modification
Rilpivirine: Histamine H2 Receptor Antagonists may decrease serum concentration of Rilpivirine. Management: Administer histamine H2 receptor antagonists (H2RAs) at least 12 hours before or 4 hours after oral rilpivirine. Risk D: Consider Therapy Modification
Risedronate: Histamine H2 Receptor Antagonists may increase serum concentration of Risedronate. This applies specifically to delayed-release risedronate. Risk X: Avoid
Roflumilast-Containing Products: Cimetidine may increase serum concentration of Roflumilast-Containing Products. Cimetidine may increase active metabolite exposure of Roflumilast-Containing Products. Risk C: Monitor
Saquinavir: Histamine H2 Receptor Antagonists may increase serum concentration of Saquinavir. Management: Consider alternatives to this combination for patients taking the Invirase formulation of saquinavir. No action beyond standard clinical care measures is required for patients taking the Fortovase formulation of saquinavir. Risk D: Consider Therapy Modification
Secretin: Coadministration of Histamine H2 Receptor Antagonists and Secretin may alter diagnostic results. Specifically, use of H2-Antagonists may cause a hyperresponse in gastrin secretion in response to secretin stimulation testing, falsely suggesting gastrinoma. Management: Avoid concomitant use of histamine H2-antagonists (H2RAs) and secretin. Discontinue H2RAs at least 2 days prior to secretin administration. Risk D: Consider Therapy Modification
Selpercatinib: Histamine H2 Receptor Antagonists may decrease serum concentration of Selpercatinib. Management: Coadministration of selpercatinib and H2 receptor antagonists should be avoided. If coadministration cannot be avoided, selpercatinib should be administered 2 hours before or 10 hours after H2 receptor antagonists. Risk D: Consider Therapy Modification
Sertindole: Cimetidine may increase serum concentration of Sertindole. Risk X: Avoid
Simvastatin: CYP3A4 Inhibitors (Weak) may increase serum concentration of Simvastatin. CYP3A4 Inhibitors (Weak) may increase active metabolite exposure of Simvastatin. Risk C: Monitor
Sirolimus (Conventional): CYP3A4 Inhibitors (Weak) may increase serum concentration of Sirolimus (Conventional). Risk C: Monitor
Sirolimus (Protein Bound): CYP3A4 Inhibitors (Weak) may increase serum concentration of Sirolimus (Protein Bound). Management: Reduce the dose of protein bound sirolimus to 56 mg/m2 when used concomitantly with a weak CYP3A4 inhibitor. Risk D: Consider Therapy Modification
Sotorasib: Histamine H2 Receptor Antagonists may decrease serum concentration of Sotorasib. Risk X: Avoid
Sparsentan: Histamine H2 Receptor Antagonists may decrease serum concentration of Sparsentan. Risk X: Avoid
Sulpiride: Histamine H2 Receptor Antagonists may decrease serum concentration of Sulpiride. Management: Consider alternatives to this combination, such as antacids given 2 hours after sulpiride, if possible. This does not apply when sulpiride and H2RAs are intentionally coadministered for the treatment of duodenal ulcers. Risk D: Consider Therapy Modification
Tacrolimus (Systemic): CYP3A4 Inhibitors (Weak) may increase serum concentration of Tacrolimus (Systemic). Risk C: Monitor
Tamsulosin: Cimetidine may increase serum concentration of Tamsulosin. Risk C: Monitor
Theophylline Derivatives: CYP1A2 Inhibitors (Weak) may increase serum concentration of Theophylline Derivatives. Risk C: Monitor
Thioridazine: CYP2D6 Inhibitors (Weak) may increase serum concentration of Thioridazine. Management: Consider avoiding concomitant use of thioridazine and weak CYP2D6 inhibitors. If combined, monitor closely for QTc interval prolongation and arrhythmias. Some weak CYP2D6 inhibitors list use with thioridazine as a contraindication. Risk D: Consider Therapy Modification
TiZANidine: CYP1A2 Inhibitors (Weak) may increase serum concentration of TiZANidine. Management: Avoid the use of tizanidine with weak CYP1A2 inhibitors when possible. If combined, monitor closely for increased tizanidine toxicities (eg, hypotension, bradycardia, drowsiness). Tizanidine dose reduction or discontinuation may be necessary. Risk D: Consider Therapy Modification
TOLBUTamide: Cimetidine may increase serum concentration of TOLBUTamide. Risk C: Monitor
Triazolam: CYP3A4 Inhibitors (Weak) may increase serum concentration of Triazolam. Risk C: Monitor
Tricyclic Antidepressants: Cimetidine may increase serum concentration of Tricyclic Antidepressants. Risk C: Monitor
Ubrogepant: CYP3A4 Inhibitors (Weak) may increase serum concentration of Ubrogepant. Management: In patients taking weak CYP3A4 inhibitors, the initial and second dose (given at least 2 hours later if needed) of ubrogepant should be limited to 50 mg. Risk D: Consider Therapy Modification
Urapidil: Cimetidine may increase hypotensive effects of Urapidil. Risk C: Monitor
Velpatasvir: Histamine H2 Receptor Antagonists may decrease serum concentration of Velpatasvir. Risk C: Monitor
Vitamin K Antagonists: Cimetidine may increase anticoagulant effects of Vitamin K Antagonists. Management: Avoid coadministration of cimetidine and vitamin K antagonists. If unavoidable, monitor for increased effects of vitamin K antagonists when cimetidine is initiated/dose increased, or decreased effects if cimetidine is discontinued/dose decreased. Risk D: Consider Therapy Modification
Zaleplon: Cimetidine may increase serum concentration of Zaleplon. Management: The initial dose of zaleplon should be limited to 5 mg in patients taking cimetidine. Monitor patients for increased zaleplon effects/toxicities (ie, sedation, CNS depression) when these agents are combined. Risk D: Consider Therapy Modification
ZOLMitriptan: Cimetidine may increase serum concentration of ZOLMitriptan. Management: Limit the maximum single dose of zolmitriptan to 2.5 mg, not to exceed 5 mg in 24 hours, when coadministered with cimetidine. Risk D: Consider Therapy Modification
Prolonged treatment (≥2 years) may lead to malabsorption of dietary vitamin B12 and subsequent vitamin B12 deficiency (Lam 2013).
Cimetidine crosses the placenta (Howe 1981). Histamine H2 antagonists have been evaluated for the treatment of gastroesophageal reflux disease (GERD), as well as gastric and duodenal ulcers during pregnancy (Cappell 2003; Richter 2003). Histamine H2 antagonists may be used for aspiration prophylaxis prior to cesarean delivery (ASA 2007).
CBC, gastric pH, occult blood with GI bleeding; renal function
Competitive inhibition of histamine at H2 receptors of the gastric parietal cells resulting in reduced gastric acid secretion, gastric volume and hydrogen ion concentration reduced
Onset of action: 1 hour
Duration: 80% reduction in gastric acid secretion for 4 to 5 hours after 300 mg dose
Absorption: Rapid
Distribution: Children and Adolescents: 1.23 ± 0.45 L/kg (Lloyd 1985b); Adults: 1 to 1.5 L/kg (Somogyi 1983)
Protein binding: 20% (Somogyi 1983)
Metabolism: Partially hepatic, forms metabolites (Somogyi 1983)
Bioavailability: ~60% to 70% (Somogyi 1983)
Half-life elimination: Neonates: 3.6 hours (Lloyd 1985a); Children and Adolescents: 1.39 ± 0.25 hours (Lloyd 1985b); Adults: ~2 hours
Time to peak, serum: Oral: 0.75 to 1.5 hours
Excretion: Primarily urine (48% as unchanged drug); feces (2%) (Somogyi 1983)
Altered kidney function: Drug accumulation may occur in patients with severe kidney failure.