Diphenhydramine: adverse event reports filed with FDA

15,339

reports as suspect product

0.1% of all reports · about 687 a year

1,157

reports, 12 months to June 2026

1,301 in the 12 months before

96%

marked serious by the reporter

57.7% across the class

57.6%

record death among outcomes, as reported

8,831 reports · not verified by FDA

Reports by month, five years

Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

By year received

2026 covers reports received through June 2026 only.

Reactions recorded in the reports

share of Diphenhydramine reports recording the termmedian drug in histamine-1 receptor antagonist

1. Toxicity to various agentspoisoning or toxic effect of one or more substances24.7%3,795
2. Completed suicidedeath by suicide19.8%3,030
3. Drug abusemisuse of a medicine12.9%1,975
4. Drug ineffectivethe medicine did not work as expected11.9%1,827
5. Off label useused for a purpose or in a way not on the label8.7%1,330
6. Overdosea dose above the recommended amount7.4%1,131
7. Headachehead pain6.3%963
8. Deaththe patient died; cause not stated by this term6%915
9. Painpain, site not specified5.9%906
10. Fatiguetiredness5.8%885
11. Infusion related reactiona reaction during or soon after an infusion5.5%849
12. Cardio-respiratory arrestthe heart and breathing stopped5.1%783
13. Hypertensionhigh blood pressure4.8%737
14. Cardiac arrestthe heart stopped4.7%721
15. Pyrexiafever4.7%716
16. Nauseafeeling sick4.6%708
17. Rheumatoid arthritisrheumatoid arthritis, an inflammatory joint disease4.5%695
18. Intentional product misusedeliberate use not as intended4.3%660
19. Hypersensitivityan allergic-type reaction4.3%652
20. Hepatic enzyme increasedraised liver enzymes3.8%588
21. Rashskin rash3.8%580
22. Drug hypersensitivityan allergic-type reaction to a medicine3.7%561
23. Asthmaasthma3.5%539
24. Exposure during pregnancythe medicine was taken during pregnancy3.5%530
25. Product use issuea problem in how the product was used3.4%526
26. Intentional overdosea deliberate overdose3.4%515
27. Erythemaskin redness3.3%502
28. Constipationconstipation3.2%486
29. Hyperhidrosisexcessive sweating3.1%477
30. Malaisegeneral feeling of being unwell3.1%476

Top 30 of 1,424 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 34 drugs in the histamine-1 receptor antagonist class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Outcomes recorded

Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 135,666 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."

Patients and reporters

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 71.9% of reports give the United States as the country of the event or reporter.

Reason for use recorded

The indication field is filled in by the reporter and is often blank; shares are of all 15,339 reports.

Drugs most often listed in the same reports

Other products listed in reports where Diphenhydramine is a suspect product, whatever their own role. Co-listing means the two were recorded together; it says nothing about either product's part in the event. Only the 2,500 most-reported names are counted here.

In context

Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Other drugs in the histamine-1 receptor antagonist class

Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.

Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Diphenhydramine as a suspect or interacting product; reports listing it only as a concomitant medication (48,575) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.