Drug profile

The FDA adverse-event record for Benadryl

252 FDA reports name Benadryl, a high-volume drug in the CVM extract. Species, reactions, and outcomes follow.

#477 of 2,679
by report volume (all drugs)
252
adverse-event reports
14.3%
death-coded share
Dog
most-reported species

Corpus placement

According to the FDA Center for Veterinary Medicine openFDA adverse-event extract, Benadryl ranks #477 of 2679 by total reports (252) and #389 of 1130 by death-coded share (14.3%). National dual: Milbemycin Oxime + Spinosad is #1 of 2679 drugs by total adverse-event reports (149,624) at death-coded-share rank 965 of 1130 drugs with at least 50 reports (2.3%); separately, Atlantic Salmon Transgenic Whole (Opafp-Ghc2 Rdna Construct Inserted Into The A-Locus In The Eo-1A Lineage) is #1 highest death-coded share at 97.8% (report rank #821).

149,624
Milbemycin Oxime + Spinosad reports (#1)
97.8%
Atlantic Salmon Transgenic Whole (Opafp-Ghc2 Rdna Construct Inserted Into The A-Locus In The Eo-1A Lineage) death share (#1)
#477
This drug, reports of 2679
#389
This drug, death share of 1130

Report volume reflects how common a breed or drug is and how often owners and vets file — not actual risk. Death-coded share ranks are limited to entries with enough reports to be meaningful. The two maps do not agree at #1.

Release-over-release change

What changed in the latest FDA data snapshot

PlainBreed reconstructed the prior snapshot from dated openFDA partitions through 2025 Q4, then compared it with the 2026-07-27 openFDA export. Benadryl has 252 reports now versus 250 in that prior snapshot: 2 more (0.8%).

Report change
+2
Death-coded reports
+0
Death-coded share
−0.1 pts

This compares reported-event counts in two source snapshots. It does not establish a change in real-world risk, product safety, or disease incidence.

Subscribe to Benadryl changes

Signature read: death-coded report count at 36 is the most distinctive stamp on Benadryl's FDA AER row.

Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
252
Total Reports
36
Deaths Reported
14.3%
Death-coded share of reports

Active Ingredients

Benadryl

Administration Routes

UnknownOralIntramuscularSubcutaneousIntravenous

Species Affected

Dog 229
Cat 23

Most Affected Breeds

Retriever - Labrador 22
Domestic Shorthair 16
Crossbred Canine/dog 13
Boxer (German Boxer) 12
Chihuahua 11
Shepherd Dog - German 11
Terrier - Bull - American Pit 10
Terrier - Boston 10
Shih Tzu 8
Dachshund (unspecified) 8

Most Reported Reactions

Vomiting 51
Lethargy (see also Central nervous system depression in Neurological) 36
Diarrhoea 35
Not eating 31
Facial swelling (see also Skin) 23
Hives (see also Skin) 23
Lethargy (see also Central nervous system depression in 'Neurological') 21
Death 20
Seizure NOS 20
Emesis (multiple) 19
Panting 19
Itching 18

Outcome Breakdown

Ongoing
148 (58.7%)
Recovered/Normal
40 (15.9%)
Outcome Unknown
28 (11.1%)
Died
21 (8.3%)
Euthanized
15 (6.0%)

Benadryl: high report volume in the FDA AER row

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.

High-volume nationwide drug peers

Two openFDA-derived peer sets for Benadryl, both floored at ≥50 reports so the neighborhoods stay in the advertised mass.

Similar death-coded share

Nearest other drugs by death-coded share (14.3% here), distinct from the volume row.

What to do with this drug

A report does not prove a drug caused the reaction; consult a veterinarian before acting on this data.

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

openFDA Animal & Veterinary Adverse Events (FDA CVM) for Benadryl (#477 of 2,679 by report volume); death-coded 14.3%. PlainBreed drug row · death-coded report count stamp 36 · vintage 2025.

Informational only. FDA adverse-event reports are voluntary and do not prove causation; consult a veterinarian before acting on them. Verify with FDA CVM →