Cimetidine Side Effects

ADVERSE REACTIONS Adverse effects reported in patients taking cimetidine tablets are described as follows by body system.

Incidence figures of 1 in 100 and greater are generally derived from controlled clinical studies.

Gastrointestinal Diarrhea (usually mild) has been reported in approximately 1 in 100 patients.

CNS Headaches, ranging from mild to severe, have been reported in 3.5% of 924 patients taking 1,600 mg/day, 2.1% of 2,225 patients taking 800 mg/day and 2.3% of 1,897 patients taking placebo.

Dizziness and somnolence (usually mild) have been reported in approximately 1 in 100 patients on either 1,600 mg/day or 800 mg/day.

Reversible confusional states, e.g., mental confusion, agitation, psychosis, depression, anxiety, hallucinations, disorientation, have been reported predominantly, but not exclusively, in severely ill patients.

They have usually developed within 2 to 3 days of initiation of treatment with cimetidine tablets and have cleared within 3 to 4 days of discontinuation of the drug.

Endocrine Gynecomastia has been reported in patients treated for 1 month or longer.

In patients being treated for pathological hypersecretory states, this occurred in about 4% of cases while in all others the incidence was 0.3% to 1% in various studies.

No evidence of induced endocrine dysfunction was found, and the condition remained unchanged or returned toward normal with continuing treatment with cimetidine tablets.