Drug profile

The FDA adverse-event record for Zonisamide

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

#414 of 2,679
by report volume (all drugs)
307
adverse-event reports
14.7%
death-coded share
Dog
most-reported species

Corpus placement

According to the FDA Center for Veterinary Medicine openFDA adverse-event extract, Zonisamide ranks #414 of 2679 by total reports (307) and #376 of 1130 by death-coded share (14.7%). 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)
#414
This drug, reports of 2679
#376
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. Zonisamide has 307 reports now versus 298 in that prior snapshot: 9 more (3.0%).

Report change
+9
Death-coded reports
+3
Death-coded share
+0.6 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 Zonisamide changes

Signature read: death-coded report count at 45 is the most distinctive stamp on Zonisamide'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.
307
Total Reports
45
Deaths Reported
14.7%
Death-coded share of reports

Active Ingredients

Zonisamide

Administration Routes

OralUnknown

Species Affected

Dog 297
Cat 9
Human 1

Most Affected Breeds

Retriever - Labrador 32
Dog (unknown) 22
Shih Tzu 14
Chihuahua 13
Shepherd Dog - Australian 12
Siberian Husky 11
Crossbred Canine/dog 9
Shepherd Dog - German 8
Maltese 7
Retriever - Golden 7

Most Reported Reactions

Seizure NOS 112
Vomiting 41
Lethargy (see also Central nervous system depression in 'Neurological') 31
Death by euthanasia 29
Diarrhoea 28
Ataxia 22
Lethargy (see also Central nervous system depression in Neurological) 21
Not eating 20
Anorexia 18
Other abnormal test result NOS 18
Lack of efficacy - NOS 18
Elevated alanine aminotransferase (ALT) 16

Outcome Breakdown

Ongoing
95 (31.4%)
Recovered/Normal
88 (29.0%)
Outcome Unknown
72 (23.8%)
Euthanized
29 (9.6%)
Died
16 (5.3%)
Recovered with Sequela
3 (1.0%)

Zonisamide: 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 Zonisamide, both floored at ≥50 reports so the neighborhoods stay in the advertised mass.

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 Zonisamide (#414 of 2,679 by report volume); death-coded 14.7%. PlainBreed drug row · death-coded report count stamp 45 · 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 →