Seizures after Fipronil + S-methoprene (Frontline Plus) in dogs

214 reports to the FDA describe seizures in dogs given Fipronil + S-methoprene. That is 7.2% of all reports for this medicine, compared with 4.4% across reports for all dog medicines, so it is reported unusually often with this medicine.

214Reports

86%Marked serious

49%Recovered

9.8%Died or euthanised

12 daysTypical onset

How soon it started

Same day

25 23%

1–2 days

14 13%

3–7 days

10 9.1%

1–4 weeks

24 22%

Over a month

37 34%

How the animals did

Recovered

105 49%

Still unwell when reported

16 7.5%

Died

9 4.2%

Euthanised

12 5.6%

Not known

72 34%

Problems reported at the same time

28 13%

27 13%

25 12%

22 10%

17 7.9%

15 7.0%

14 6.5%

14 6.5%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Fipronil kills fleas and ticks (spot-on).

Products with this combination include Frontline Plus. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

Questions owners ask

Can Fipronil + S-methoprene cause seizures in dogs?: 214 reports link the two, but a report alone does not prove the medicine was the cause: other illnesses, other medicines or coincidence can be involved. Your vet can judge it for your animal.
How soon after a dose was it reported?: In half of the reports with dates, it started within 12 days of the first dose.
What should I do?: Don't give another dose until you've spoken to your vet, and keep the packaging so you can tell them the product and dose. Your vet can also report it to the FDA (or you can, through the manufacturer or FDA form 1932a).

Seizures with similar medicines

Seizures after Spinosad (Comfortis) 2,116 reports · 3.7% of its reports
Seizures after Lufenuron + Milbemycin Oxime (Sentinel) 937 reports · 3.6% of its reports
Seizures after Imidacloprid + Moxidectin (Advantage Multi) 520 reports · 4.0% of its reports
Seizures after Nitenpyram (Capstar) 331 reports · 3.1% of its reports
Seizures after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 279 reports · 2.8% of its reports
Seizures after Flumethrin + Imidacloprid (Seresto) 123 reports · 5.4% of its reports
Seizures after Imidacloprid 43 reports · 2.3% of its reports
Seizures after Fipronil 72 reports · 5.1% of its reports
Seizures after Lufenuron 65 reports · 6.4% of its reports
Seizures after Imidacloprid + Permethrin + Pyriproxyfen 34 reports · 4.6% of its reports

All reported side effects of Fipronil + S-methoprene in dogs · Medicines most reported with seizures