Note: This document contains side effect information about cimetidine. Some dosage forms listed on this page may not apply to the brand name Tagamet HB.

Summary

More frequent side effects include: gynecomastia. Continue reading for a comprehensive list of adverse effects.

Applies to cimetidine: oral liquid and tablets, parenteral injection, parenteral injection for iv infusion only.

Side effects include:

Headache, dizziness, somnolence, diarrhea.

With ≥1 month of therapy: gynecomastia.

With IM therapy: transient pain at injection site.

For Healthcare Professionals

Applies to cimetidine: compounding powder, intravenous solution, oral liquid, oral tablet.

Renal

Very common (10% or more): Increased plasma creatinine (up to 11%)

Rare (0.01% to 0.1%): Interstitial nephritis^[Ref]

Interstitial nephritis cleared with drug withdrawal.

Creatinine elevations usually occurred during the first week of treatment and were typically non-progressive, with values returning to pretreatment levels during therapy or up to 1 week after stopping treatment.^[Ref]

Gastrointestinal

Common (1% to 10%): Constipation, diarrhea, flatulence, nausea, vomiting

Rare (0.01% to 0.1%): Acute pancreatitis/pancreatitis^[Ref]

Pancreatitis cleared with drug withdrawal.^[Ref]

Musculoskeletal

Common (1% to 10%): Musculoskeletal pain, myalgia/reversible myalgia

Rare (0.01% to 0.1%): Arthralgia/reversible arthralgia, exacerbation of joint symptoms, polymyositis^[Ref]

Nervous system

Common (1% to 10%): Dizziness, drowsiness, headache^[Ref]

Headaches occurred more frequently in patients given 1600 mg/day compared to patients given 800 mg/day.

Somnolence and dizziness were usually mild and have been reported in patients receiving 800 to 1600 mg/day.^[Ref]

Dermatologic

Common (1% to 10%): Rash/skin rashes

Rare (0.01% to 0.1%): Hypersensitivity vasculitis

Very rare (less than 0.01%): Epidermal necrolysis, erythema multiforme, generalized exfoliative erythroderma, reversible alopecia, severe generalized skin reactions, Stevens-Johnson syndrome

Frequency not reported: Severe skin rash^[Ref]

Hypersensitivity vasculitis usually cleared with drug withdrawal.^[Ref]

Other

Fever cleared with drug withdrawal.^[Ref]

Common (1% to 10%): Tiredness

Rare (0.01% to 0.1%): Fever^[Ref]

Psychiatric

Confusional states occurred within 2 to 3 days of starting treatment, were reversible within 3 to 4 days of stopping treatment and were more commonly reported in elderly patients and/or ill patients (e.g., renal dysfunction, organic brain syndrome).^[Ref]

Uncommon (0.1% to 1%): Confusional state, depression, hallucination

Frequency not reported: Agitation, anxiety, disorientation, mental confusion, psychosis^[Ref]

Hepatic

Uncommon (0.1% to 1%): Hepatitis, reversible liver damage

Rare (0.01% to 0.1%): Cholestatic effects, increased serum transaminases, mixed cholestatic-hepatocellular effects

Very rare (less than 0.01%): Fatal hepatic effects

Frequency not reported: Periportal hepatic fibrosis, severe parenchymal injury^[Ref]

Hepatitis and serum transaminase level elevations cleared with drug withdrawal.

Fatal hepatic effects have occurred with other histamine-2 receptor antagonists.

Severe parenchymal injury is considered highly unlikely due to the predominance of cholestatic features.

There was a report of biopsy-proven periportal hepatic fibrosis in a patient receiving this drug.^[Ref]

Hematologic

Uncommon (0.1% to 1%): Leukopenia

Rare (0.01% to 0.1%): Agranulocytosis, aplastic anemia, decreased white blood cell counts, pancytopenia, thrombocytopenia

Very rare (less than 0.01%): Immune hemolytic anemia^[Ref]

Leukopenia and/or thrombocytopenia were reversible with withdrawal of treatment.

Agranulocytosis/decreased white blood cell counts have been reported, with some events recurring upon rechallenge. These events were more commonly reported in patients with serious concomitant illnesses and/or those who received drugs/treatments known to produce neutropenia.^[Ref]

Cardiovascular

Uncommon (0.1% to 1%): Tachycardia

Rare (0.01% to 0.1%): Atrioventricular (AV) heart block/heart block, sinus bradycardia^[Ref]

Genitourinary

Uncommon (0.1% to 1%): Reversible impotence

Rare (0.01% to 0.1%): Urinary retention

Very rare (less than 0.01%): Galactorrhea^[Ref]

Urinary retention cleared with drug withdrawal.^[Ref]

Endocrine

Uncommon (0.1% to 1%): Gynecomastia^[Ref]

Hypersensitivity

Allergic reactions and anaphylaxis usually cleared with drug withdrawal.^[Ref]

Rare (0.01% to 0.1%): Allergic reactions, anaphylaxis^[Ref]

Immunologic

Very rare (less than 0.01%): Strongyloidiasis hyperinfection^[Ref]

Respiratory

In a large epidemiological study, it was suggested that patients taking histamine-2-receptor antagonists had an increased adjusted relative risk of 1.63 (95% confidence interval of 1.07 to 2.48) of developing pneumonia compared to patients who stopped treatment. However, causal relationship between H2RA use and pneumonia has not been established.^[Ref]

Frequency not reported: Pneumonia^[Ref]