Drug profile

The FDA adverse-event record for Zonisamide

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

289
adverse-event reports
14.5%
death-coded share
Dog
most-reported species
107
Seizure NOS - top reaction
Verify with FDA CVM →
Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
289
Total Reports
42
Deaths Reported
14.5%
Death Rate

Active Ingredients

Zonisamide

Administration Routes

OralUnknown

Species Affected

Dog 280
Cat 8
Human 1

Most Affected Breeds

Retriever - Labrador 31
Dog (unknown) 21
Shih Tzu 14
Chihuahua 12
Shepherd Dog - Australian 12
Siberian Husky 10
Shepherd Dog - German 8
Crossbred Canine/dog 8
Maltese 7
Dachshund (unspecified) 6

Most Reported Reactions

Seizure NOS 107
Vomiting 40
Lethargy (see also Central nervous system depression in 'Neurological') 31
Death by euthanasia 26
Diarrhoea 24
Ataxia 22
Lethargy (see also Central nervous system depression in Neurological) 20
Lack of efficacy - NOS 18
Anorexia 15
Other abnormal test result NOS 15
Elevated alanine aminotransferase (ALT) 15
Not eating 15

Outcome Breakdown

Ongoing
89 (31.2%)
Recovered/Normal
85 (29.8%)
Outcome Unknown
66 (23.2%)
Euthanized
26 (9.1%)
Died
16 (5.6%)
Recovered with Sequela
3 (1.1%)

Zonisamide Adverse Event Insights

289 reports name Zonisamide; 42 recorded a death outcome (14.5% of reported events, not a population-level mortality rate). Active ingredient: Zonisamide. Administration routes: Oral, Unknown.

By species: Dog (280 reports), Cat (8 reports), Human (1 reports). By breed: Retriever - Labrador (31), Dog (unknown) (21), Shih Tzu (14).

Leading clinical signs: Seizure NOS (107), Vomiting (40), Lethargy (see also Central nervous system depression in 'Neurological') (31), Death by euthanasia (26). Outcome, 285 coded reports: Ongoing leads at 31.2%.

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.