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

The FDA has received 73 reports of drooling in dogs after Fipronil + S-methoprene. That is 2.5% of all reports for this medicine, compared with 1.4% across reports for all dog medicines, so it is reported unusually often with this medicine.

73Reports

71%Marked serious

44%Recovered

6.8%Died or euthanised

21 daysTypical onset

How soon it started

Same day

7 16%

1–2 days

5 11%

3–7 days

0 0.0%

1–4 weeks

11 25%

Over a month

21 48%

How the animals did

Recovered

31 42%

Recovered with lasting effects

1 1.4%

Still unwell when reported

6 8.2%

Died

2 2.7%

Euthanised

3 4.1%

Not known

30 41%

Problems reported at the same time

23 32%

22 30%

17 23%

15 21%

12 16%

Restlessness or agitation

10 14%

Loss of appetite

10 14%

Wobbliness (ataxia)

10 14%

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 drooling in dogs?: 73 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 21 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).

Drooling with similar medicines

Drooling after Spinosad (Comfortis) 878 reports · 1.5% of its reports
Drooling after Lufenuron + Milbemycin Oxime (Sentinel) 270 reports · 1.0% of its reports
Drooling after Imidacloprid + Moxidectin (Advantage Multi) 399 reports · 3.0% of its reports
Drooling after Nitenpyram (Capstar) 158 reports · 1.5% of its reports
Drooling after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 112 reports · 1.1% of its reports
Drooling after Flumethrin + Imidacloprid (Seresto) 24 reports · 1.1% of its reports
Drooling after Fipronil 24 reports · 1.7% of its reports

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