Note: This document contains side effect information about cimetidine. Some of the dosage forms listed on this page may not apply to the brand name Tagamet HB.
More frequent side effects include: gynecomastia. See below 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.
Applies to cimetidine: compounding powder, intravenous solution, oral liquid, oral tablet
Very common (10% or more): Increased plasma creatinine (up to 11%)
Rare (0.01% to 0.1%): Interstitial nephritis
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.
Common (1% to 10%): Constipation, diarrhea, flatulence, nausea, vomiting
Rare (0.01% to 0.1%): Acute pancreatitis/pancreatitis
Pancreatitis cleared with drug withdrawal.
Common (1% to 10%): Musculoskeletal pain, myalgia/reversible myalgia
Rare (0.01% to 0.1%): Arthralgia/reversible arthralgia, exacerbation of joint symptoms, polymyositis
Common (1% to 10%): Dizziness, drowsiness, headache
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.
Hypersensitivity vasculitis usually cleared with drug withdrawal.
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
Fever cleared with drug withdrawal.
Common (1% to 10%): Tiredness
Rare (0.01% to 0.1%): Fever
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).
Uncommon (0.1% to 1%): Confusional state, depression, hallucination
Frequency not reported: Agitation, anxiety, disorientation, mental confusion, psychosis
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.
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
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
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.
Uncommon (0.1% to 1%): Tachycardia
Rare (0.01% to 0.1%): Atrioventricular (AV) heart block/heart block, sinus bradycardia
Urinary retention cleared with drug withdrawal.
Uncommon (0.1% to 1%): Reversible impotence
Rare (0.01% to 0.1%): Urinary retention
Very rare (less than 0.01%): Galactorrhea
Uncommon (0.1% to 1%): Gynecomastia
Allergic reactions and anaphylaxis usually cleared with drug withdrawal.
Rare (0.01% to 0.1%): Allergic reactions, anaphylaxis
Very rare (less than 0.01%): Strongyloidiasis hyperinfection
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.
Frequency not reported: Pneumonia
Medically reviewed by BestRx Medical Team Last updated on 1/1/2020.
Source: Drugs.com Tagamet Hb