Drug profile

The FDA adverse-event record for Phenobarbital

1,560 adverse-event reports submitted to the FDA Center for Veterinary Medicine reference Phenobarbital. See the species affected, top reactions, and outcomes below.

1,560
adverse-event reports
12.3%
death-coded share
Dog
most-reported species
593
Seizure NOS - 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.
1,560
Total Reports
192
Deaths Reported
12.3%
Death Rate

Active Ingredients

Phenobarbital

Administration Routes

OralUnknownIntravenousRectalSubcutaneousOtherParenteral

Species Affected

Dog 1,442
Cat 113
Unknown 4
Other Canids 1

Most Affected Breeds

Retriever - Labrador 127
Chihuahua 87
Domestic Shorthair 63
Retriever - Golden 62
Crossbred Canine/dog 58
Shepherd Dog - German 50
Dog (unknown) 48
Terrier - Yorkshire 46
Shepherd Dog - Australian 45
Beagle 42

Most Reported Reactions

Seizure NOS 593
Lethargy (see also Central nervous system depression in 'Neurological') 183
Vomiting 155
Death by euthanasia 114
Other abnormal test result NOS 105
Emesis 93
Lack of efficacy - NOS 93
Ataxia 90
Diarrhoea 84
Death 76
Behavioural disorder NOS 74
Anorexia 74

Outcome Breakdown

Recovered/Normal
475 (30.7%)
Ongoing
455 (29.4%)
Outcome Unknown
364 (23.5%)
Euthanized
109 (7.0%)
Died
83 (5.4%)
Recovered with Sequela
63 (4.1%)

Phenobarbital Adverse Event Insights

1,560 reports name Phenobarbital; 192 recorded a death outcome (12.3% of reported events, not a population-level mortality rate). Active ingredient: Phenobarbital. Administration routes: Oral, Unknown, Intravenous, Rectal.

By species: Dog (1,442 reports), Cat (113 reports), Unknown (4 reports). By breed: Retriever - Labrador (127), Chihuahua (87), Domestic Shorthair (63).

Leading clinical signs: Seizure NOS (593), Lethargy (see also Central nervous system depression in 'Neurological') (183), Vomiting (155), Death by euthanasia (114). Outcome, 1,549 coded reports: Recovered/Normal leads at 30.7%.

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.