Diphenhydramine — FDA Animal & Veterinary Adverse Event (ADE) Reports
Source: openFDA animalandveterinary/event.json, the FDA Center for Veterinary Medicine (CVM) adverse event report database. Data pulled 2026-07-22. Counts are report-level: one report may list multiple reactions and multiple animals, so figures are not additive and do not imply causation. Diphenhydramine is a active ingredient.
Total reports
Diphenhydramine: 2816
Reports by species (top entries)
- Dog 2592
- Cat 204
- Human 16
- Ferret 2
- Horse 1
Top reported reactions (VEDDRA terms, top entries)
- Vomiting 629
- Emesis 342
- Diarrhoea 335
- Lethargy (see also Central nervous system depression in 'Neurological') 324
- Lethargy (see also Central nervous system depression in Neurological) 275
- Lack of efficacy - NOS 195
- Not eating 195
- Injection site swelling 170
- Anaphylaxis 161
- Emesis (multiple) 160
Source JSON: pdf-raw/ade/ade_active_ingredients_2026-07-22_b9.json (openFDA animalandveterinary/event.json, pulled 2026-07-22).