Diphenhydramine hcl: adverse event reports filed with FDA

2,741

reports as suspect product

0% of all reports · about 122 a year

0

reports, 12 months to June 2026

0 in the 12 months before

91%

marked serious by the reporter

57.7% across the class

68.4%

record death among outcomes, as reported

1,875 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

Reactions recorded in the reports

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

1. Completed suicidedeath by suicide26.6%730
2. Toxicity to various agentspoisoning or toxic effect of one or more substances11.8%323
3. Deaththe patient died; cause not stated by this term11.1%305
4. Cardiac arrestthe heart stopped10.8%297
5. Respiratory arrestbreathing stopped9.7%266
6. Cardio-respiratory arrestthe heart and breathing stopped8.3%227
7. Drug toxicity8.1%223
8. Drug abusemisuse of a medicine5.9%163
9. Drug hypersensitivityan allergic-type reaction to a medicine5.9%161
10. Overdosea dose above the recommended amount5.7%155
11. Intentional overdosea deliberate overdose3.3%90
12. Multiple drug overdose3.2%88
13. Poisoning3.2%87
14. Suicide attempta suicide attempt2.9%79
15. Intentional drug misuse2.5%68
16. Somnolencedrowsiness2.5%68
17. Tachycardiafast heart rate2.5%68
18. Hypotensionlow blood pressure2.3%62
19. Drug interactionan interaction between medicines2%55
20. Agitationrestlessness2%54
21. Multiple drug overdose intentional1.9%51
22. Accidental overdosean accidental overdose1.8%49
23. Drug ineffectivethe medicine did not work as expected1.8%49
24. Vomitingbeing sick1.8%49
25. Coma1.8%48
26. Convulsion1.8%48
27. Pulmonary oedemafluid in the lungs1.7%46
28. Confusional stateconfusion1.5%41
29. Deliriumsudden confusion1.5%41
30. Unresponsive to stimuli1.5%41

Top 30 of 410 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. 86.6% 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 2,741 reports.

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 hcl as a suspect or interacting product; reports listing it only as a concomitant medication (5,487) 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.