The most commonly reported side effects of diphenhydramine include off label use, fatigue, and nausea, based on 174,304 FDA adverse event reports from 2004 to 2025. 7.0% of reports found the drug to be ineffective.
Percentages show how often each reaction appears relative to total reports for diphenhydramine.
These are voluntary reports and do not establish that diphenhydramine caused these reactions.
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Other drugs that appear in adverse event reports alongside diphenhydramine. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.
Also suspected
Taken alongside
Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.
57.2% of diphenhydramine adverse event reports involve female patients and 29.1% involve male patients. The largest age group is adult at 64%. These figures reflect who reports side effects, not underlying risk.
Sex
Age group
Conditions and purposes for which patients were taking diphenhydramine when the adverse event was reported.
Showing 15 of 1,698 indications
Diphenhydramine is sold under brand names including Ibuprofen And Diphenhydramine Citrate, Naproxen Sodium And Diphenhydramine Hydrochloride.
An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.
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