Drug profile

The FDA adverse-event record for Fipronil

1,753 adverse-event reports submitted to the FDA Center for Veterinary Medicine reference Fipronil. See the species affected, top reactions, and outcomes below.

1,753
adverse-event reports
4.1%
death-coded share
Dog
most-reported species
455
Lack of efficacy (ectoparasite) - flea - 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.
1,753
Total Reports
71
Deaths Reported
4.1%
Death Rate

Active Ingredients

Fipronil

Administration Routes

TopicalUnknownOralCutaneousOtherSubcutaneousTransdermalAuricular (Otic)

Species Affected

Dog 1,283
Cat 464
Unknown 5
Human 1

Most Affected Breeds

Domestic Shorthair 248
Retriever - Labrador 135
Crossbred Canine/dog 74
Domestic Longhair 70
Terrier - Yorkshire 57
Dog (unknown) 52
Shih Tzu 50
Shepherd Dog - German 49
Cat (unknown) 48
Retriever - Golden 48

Most Reported Reactions

Lack of efficacy (ectoparasite) - flea 455
Emesis 254
Lethargy (see also Central nervous system depression in 'Neurological') 220
Vomiting 201
Lack of efficacy - NOS 121
Diarrhoea 109
Panting 83
Lack of efficacy (flea) 72
Other abnormal test result NOS 69
Seizure NOS 62
Behavioural disorder NOS 62
Pruritus 61

Outcome Breakdown

Outcome Unknown
690 (39.5%)
Recovered/Normal
629 (36.0%)
Ongoing
294 (16.8%)
Recovered with Sequela
63 (3.6%)
Died
41 (2.3%)
Euthanized
30 (1.7%)

Fipronil Adverse Event Insights

1,753 reports name Fipronil; 71 recorded a death outcome (4.1% of reported events, not a population-level mortality rate). Active ingredient: Fipronil. Administration routes: Topical, Unknown, Oral, Cutaneous.

By species: Dog (1,283 reports), Cat (464 reports), Unknown (5 reports). By breed: Domestic Shorthair (248), Retriever - Labrador (135), Crossbred Canine/dog (74).

Leading clinical signs: Lack of efficacy (ectoparasite) - flea (455), Emesis (254), Lethargy (see also Central nervous system depression in 'Neurological') (220), Vomiting (201). Outcome, 1,747 coded reports: Outcome Unknown leads at 39.5%.

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.