Drug profile

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

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

812
adverse-event reports
6.0%
death-coded share
Dog
most-reported species
255
Lack of efficacy (ectoparasite) - flea - top reaction
Verify with FDA CVM →
Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
812
Total Reports
49
Deaths Reported
6.0%
Death Rate

Active Ingredients

FipronilFipronil + S-MethopreneS-Methoprene

Administration Routes

TopicalOtherUnknownOralSubconjunctival

Species Affected

Dog 762
Cat 49
Goat 1

Most Affected Breeds

Dog (unknown) 54
Retriever - Labrador 51
Retriever - Golden 47
Crossbred Canine/dog 39
Chihuahua 38
Spaniel - King Charles Cavalier 32
Terrier - Yorkshire 30
Shepherd Dog - German 27
Shih Tzu 23
Domestic Shorthair 22

Most Reported Reactions

Lack of efficacy (ectoparasite) - flea 255
Vomiting 86
Seizure NOS 58
Lack of efficacy (ectoparasite) - tick NOS 52
Lethargy (see also Central nervous system depression in 'Neurological') 49
Diarrhoea 45
Death 28
Shaking 27
Behavioural disorder NOS 25
Lack of efficacy (bacteria) - NOS 25
Lack of efficacy (bacteria) - Borrelia 25
Lack of efficacy (tick) 23

Outcome Breakdown

Outcome Unknown
505 (62.0%)
Recovered/Normal
195 (23.9%)
Ongoing
64 (7.9%)
Died
29 (3.6%)
Euthanized
20 (2.5%)
Recovered with Sequela
2 (0.2%)

Fipronil + S-Methoprene Adverse Event Insights

812 reports name Fipronil + S-Methoprene; 49 recorded a death outcome (6.0% of reported events, not a population-level mortality rate). Active ingredients: Fipronil, Fipronil + S-Methoprene, S-Methoprene. Administration routes: Topical, Other, Unknown, Oral.

By species: Dog (762 reports), Cat (49 reports), Goat (1 reports). By breed: Dog (unknown) (54), Retriever - Labrador (51), Retriever - Golden (47).

Leading clinical signs: Lack of efficacy (ectoparasite) - flea (255), Vomiting (86), Seizure NOS (58), Lack of efficacy (ectoparasite) - tick NOS (52). Outcome, 815 coded reports: Outcome Unknown leads at 62.0%.

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.