Drug profile

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

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

140
adverse-event reports
1.4%
death-coded share
Dog
most-reported species
69
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.
140
Total Reports
2
Deaths Reported
1.4%
Death Rate

Active Ingredients

Fipronil, S-Methoprene

Administration Routes

TopicalUnknownOralCutaneousOther

Species Affected

Dog 81
Cat 57
Other 2

Most Affected Breeds

Domestic Shorthair 33
Retriever - Labrador 9
Shih Tzu 8
Domestic Mediumhair 6
Pug 4
Terrier - Yorkshire 4
Shepherd Dog - German 4
Domestic Longhair 4
Cat (unknown) 4
Pit Bull 3

Most Reported Reactions

Lack of efficacy (ectoparasite) - flea 69
Lethargy (see also Central nervous system depression in 'Neurological') 17
Diarrhoea 17
Scratching 15
Vomiting 12
Lack of efficacy - NOS 8
Panting 7
Drooling 6
Emesis 6
Anorexia 6
Licking 4
Hyperactivity 4

Outcome Breakdown

Outcome Unknown
85 (60.7%)
Recovered/Normal
35 (25.0%)
Ongoing
18 (12.9%)
Died
2 (1.4%)

Fipronil, S-Methoprene Adverse Event Insights

140 reports name Fipronil, S-Methoprene; 2 recorded a death outcome (1.4% of reported events, not a population-level mortality rate). Active ingredient: Fipronil, S-Methoprene. Administration routes: Topical, Unknown, Oral, Cutaneous.

By species: Dog (81 reports), Cat (57 reports), Other (2 reports). By breed: Domestic Shorthair (33), Retriever - Labrador (9), Shih Tzu (8).

Leading clinical signs: Lack of efficacy (ectoparasite) - flea (69), Lethargy (see also Central nervous system depression in 'Neurological') (17), Diarrhoea (17), Scratching (15). Outcome, 140 coded reports: Outcome Unknown leads at 60.7%.

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.