Drug profile

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

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

22
adverse-event reports
9.1%
death-coded share
Dog
most-reported species
11
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.
22
Total Reports
2
Deaths Reported
9.1%
Death Rate

Active Ingredients

Fipronil/(S)-Methoprene

Administration Routes

TopicalCutaneous

Species Affected

Dog 11
Cat 11

Most Affected Breeds

Domestic Shorthair 9
Boxer (German Boxer) 1
Maine Coon 1
Poodle - Toy 1
Pug 1
Beagle 1
Terrier - Yorkshire 1
Bichon Frise 1
Crossbred Canine/dog 1
Pekingese 1

Most Reported Reactions

Lack of efficacy (ectoparasite) - flea 11
Pruritus 8
Vomiting 4
Behavioural disorder NOS 3
Drug dose administration interval too long 3
Lethargy (see also Central nervous system depression in 'Neurological') 2
Diarrhoea 2
Reddening of the skin 2
Inappropriate urination 2
Weight gain 2
Application site pruritus 2
Seizure NOS 1

Outcome Breakdown

Outcome Unknown
13 (59.1%)
Recovered/Normal
5 (22.7%)
Ongoing
2 (9.1%)
Died
1 (4.5%)
Euthanized
1 (4.5%)

Fipronil/(S)-Methoprene Adverse Event Insights

22 reports name Fipronil/(S)-Methoprene; 2 recorded a death outcome (9.1% of reported events, not a population-level mortality rate). Active ingredient: Fipronil/(S)-Methoprene. Administration routes: Topical, Cutaneous.

By species: Dog (11 reports), Cat (11 reports). By breed: Domestic Shorthair (9), Boxer (German Boxer) (1), Maine Coon (1).

Leading clinical signs: Lack of efficacy (ectoparasite) - flea (11), Pruritus (8), Vomiting (4), Behavioural disorder NOS (3). Outcome, 22 coded reports: Outcome Unknown leads at 59.1%.

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.