Drug profile

The FDA adverse-event record for Fenbendazole

2,684 adverse-event reports submitted to the FDA Center for Veterinary Medicine reference Fenbendazole. See the species affected, top reactions, and outcomes below.

2,684
adverse-event reports
11.1%
death-coded share
Dog
most-reported species
659
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.
2,684
Total Reports
297
Deaths Reported
11.1%
Death Rate

Active Ingredients

Fenbendazole

Administration Routes

OralUnknownTopicalSubcutaneousOphthalmicRespiratory (Inhalation)OtherIntrauterineAuricular (Otic)Intraocular

Species Affected

Dog 2,188
Unknown 143
Cattle 141
Cat 113
Horse 31
Goat 21
Human 15
Pig 8
Turkey 4
Alpaca 3

Most Affected Breeds

Crossbred Canine/dog 278
Unknown 166
Retriever - Labrador 165
Greyhound 127
Dog (unknown) 107
Pit Bull 101
Chihuahua 95
Shepherd Dog - German 83
Retriever - Golden 81
Domestic Shorthair 77

Most Reported Reactions

Vomiting 659
Diarrhoea 372
Lack of efficacy (endoparasite) - hookworm 272
Anorexia 259
Depression 229
Death 221
Other abnormal test result NOS 132
INEFFECTIVE, HOOKS 132
Lethargy (see also Central nervous system depression in 'Neurological') 130
Lack of efficacy (endoparasite) - tapeworm 129
Emesis 83
Lack of efficacy (endoparasite) - roundworm NOS 77

Outcome Breakdown

Outcome Unknown
671 (40.1%)
Recovered/Normal
365 (21.8%)
Ongoing
328 (19.6%)
Died
259 (15.5%)
Euthanized
42 (2.5%)
Recovered with Sequela
8 (0.5%)

Fenbendazole Adverse Event Insights

2,684 reports name Fenbendazole; 297 recorded a death outcome (11.1% of reported events, not a population-level mortality rate). Active ingredient: Fenbendazole. Administration routes: Oral, Unknown, Topical, Subcutaneous.

By species: Dog (2,188 reports), Unknown (143 reports), Cattle (141 reports). By breed: Crossbred Canine/dog (278), Unknown (166), Retriever - Labrador (165).

Leading clinical signs: Vomiting (659), Diarrhoea (372), Lack of efficacy (endoparasite) - hookworm (272), Anorexia (259). Outcome, 1,673 coded reports: Outcome Unknown leads at 40.1%.

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.