Drug profile

The FDA adverse-event record for Antihistamines

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

119
adverse-event reports
5.9%
death-coded share
Dog
most-reported species
19
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.
119
Total Reports
7
Deaths Reported
5.9%
Death Rate

Active Ingredients

Antihistamines

Administration Routes

UnknownOral

Species Affected

Dog 108
Cat 11

Most Affected Breeds

Retriever - Labrador 13
Terrier - Bull - American Pit 10
Terrier - Yorkshire 8
Bulldog 7
Domestic Shorthair 6
Shepherd Dog - German 5
Terrier (unspecified) 5
Chihuahua 4
Crossbred Canine/dog 4
Bichon Frise 3

Most Reported Reactions

Vomiting 19
Lack of efficacy - NOS 17
INEFFECTIVE, ATOPY CONTROL 12
Diarrhoea 11
Lethargy (see also Central nervous system depression in 'Neurological') 11
Seizure NOS 7
Elevated serum alkaline phosphatase (SAP) 7
Behavioural disorder NOS 6
Other abnormal test result NOS 6
Erythema (for urticaria see Immune SOC) 6
Death by euthanasia 5
Polyuria 5

Outcome Breakdown

Ongoing
82 (68.9%)
Outcome Unknown
21 (17.6%)
Recovered/Normal
9 (7.6%)
Euthanized
5 (4.2%)
Died
2 (1.7%)

Antihistamines Adverse Event Insights

119 reports name Antihistamines; 7 recorded a death outcome (5.9% of reported events, not a population-level mortality rate). Active ingredient: Antihistamines. Administration routes: Unknown, Oral.

By species: Dog (108 reports), Cat (11 reports). By breed: Retriever - Labrador (13), Terrier - Bull - American Pit (10), Terrier - Yorkshire (8).

Leading clinical signs: Vomiting (19), Lack of efficacy - NOS (17), INEFFECTIVE, ATOPY CONTROL (12), Diarrhoea (11). Outcome, 119 coded reports: Ongoing leads at 68.9%.

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.