Drug profile

The FDA adverse-event record for Benadryl

246 adverse-event reports submitted to the FDA Center for Veterinary Medicine reference Benadryl. See the species affected, top reactions, and outcomes below.

246
adverse-event reports
14.2%
death-coded share
Dog
most-reported species
49
Vomiting - top reaction
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Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
246
Total Reports
35
Deaths Reported
14.2%
Death Rate

Active Ingredients

Benadryl

Administration Routes

UnknownOralIntramuscularSubcutaneousIntravenous

Species Affected

Dog 223
Cat 23

Most Affected Breeds

Retriever - Labrador 19
Domestic Shorthair 16
Crossbred Canine/dog 12
Boxer (German Boxer) 12
Chihuahua 11
Shepherd Dog - German 11
Terrier - Bull - American Pit 10
Terrier - Boston 10
Shih Tzu 8
Dachshund (unspecified) 7

Most Reported Reactions

Vomiting 49
Lethargy (see also Central nervous system depression in Neurological) 35
Diarrhoea 34
Not eating 31
Facial swelling (see also Skin) 22
Lethargy (see also Central nervous system depression in 'Neurological') 21
Hives (see also Skin) 21
Death 20
Emesis (multiple) 19
Panting 19
Seizure NOS 19
Itching 18

Outcome Breakdown

Ongoing
145 (58.9%)
Recovered/Normal
38 (15.4%)
Outcome Unknown
28 (11.4%)
Died
21 (8.5%)
Euthanized
14 (5.7%)

Benadryl Adverse Event Insights

246 reports name Benadryl; 35 recorded a death outcome (14.2% of reported events, not a population-level mortality rate). Active ingredient: Benadryl. Administration routes: Unknown, Oral, Intramuscular, Subcutaneous.

By species: Dog (223 reports), Cat (23 reports). By breed: Retriever - Labrador (19), Domestic Shorthair (16), Crossbred Canine/dog (12).

Leading clinical signs: Vomiting (49), Lethargy (see also Central nervous system depression in Neurological) (35), Diarrhoea (34), Not eating (31). Outcome, 246 coded reports: Ongoing leads at 58.9%.

Read these counts as reporting volume, not risk: per our methodology, a widely-prescribed drug will rack up more raw FDA reports in a given year than a rarely-used one at an identical true rate, so we recommend comparing within similar-exposure products rather than across the full 2025 catalog.

Source: FDA Center for Veterinary Medicine openFDA Animal & Veterinary Adverse Events (CVM AER) · 2025

Every figure on PlainBreed is rendered directly from FDA openFDA adverse event data, no number is typed in by an editor. This page draws directly on FDA openFDA data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.