Drug profile

The FDA adverse-event record for Fipronil/S-Methoprene

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

101
adverse-event reports
11.9%
death-coded share
Dog
most-reported species
24
Lethargy (see also Central nervous system depression in 'Neurological') - 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.
101
Total Reports
12
Deaths Reported
11.9%
Death Rate

Active Ingredients

Fipronil/S-Methoprene

Administration Routes

TopicalUnknownOral

Species Affected

Dog 87
Cat 14

Most Affected Breeds

Retriever - Labrador 15
Domestic Shorthair 10
Terrier - West Highland White 7
Spaniel - King Charles Cavalier 6
Chihuahua 5
Shih Tzu 5
Shepherd Dog - German 3
Shepherd Dog - Australian 3
Collie (unspecified) 2
Spaniel - Cocker American 2

Most Reported Reactions

Lethargy (see also Central nervous system depression in 'Neurological') 24
Other abnormal test result NOS 14
Vomiting 12
Diarrhoea 11
Panting 8
Seizure NOS 8
Pruritus 8
Lack of efficacy (ectoparasite) - flea 8
Decreased appetite 8
Emesis 7
Anorexia 7
Abnormal radiograph finding 7

Outcome Breakdown

Recovered/Normal
44 (43.6%)
Ongoing
28 (27.7%)
Outcome Unknown
16 (15.8%)
Euthanized
6 (5.9%)
Died
6 (5.9%)
Recovered with Sequela
1 (1.0%)

Fipronil/S-Methoprene Adverse Event Insights

101 reports name Fipronil/S-Methoprene; 12 recorded a death outcome (11.9% of reported events, not a population-level mortality rate). Active ingredient: Fipronil/S-Methoprene. Administration routes: Topical, Unknown, Oral.

By species: Dog (87 reports), Cat (14 reports). By breed: Retriever - Labrador (15), Domestic Shorthair (10), Terrier - West Highland White (7).

Leading clinical signs: Lethargy (see also Central nervous system depression in 'Neurological') (24), Other abnormal test result NOS (14), Vomiting (12), Diarrhoea (11). Outcome, 101 coded reports: Recovered/Normal leads at 43.6%.

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.