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

44 reports to the FDA describe fever in dogs given Fipronil + S-methoprene. That is 1.5% of all reports for this medicine, compared with 1.4% across reports for all dog medicines.

44Reports

77%Marked serious

41%Recovered

11%Died or euthanised

31 daysTypical onset

How soon it started

Same day

2 7.7%

1–2 days

4 15%

3–7 days

1 3.8%

1–4 weeks

6 23%

Over a month

13 50%

How the animals did

Recovered

17 39%

Recovered with lasting effects

1 2.3%

Still unwell when reported

6 14%

Died

2 4.5%

Euthanised

3 6.8%

Not known

15 34%

Problems reported at the same time

18 41%

16 36%

15 34%

12 27%

9 20%

8 18%

7 16%

7 16%

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 fever in dogs?: 44 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 31 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).

Fever with similar medicines

Fever after Spinosad (Comfortis) 412 reports · 0.7% of its reports
Fever after Lufenuron + Milbemycin Oxime (Sentinel) 178 reports · 0.7% of its reports
Fever after Imidacloprid + Moxidectin (Advantage Multi) 165 reports · 1.3% of its reports
Fever after Nitenpyram (Capstar) 78 reports · 0.7% of its reports
Fever after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 35 reports · 0.4% of its reports
Fever after Flumethrin + Imidacloprid (Seresto) 31 reports · 1.4% of its reports
Fever after Lufenuron 41 reports · 4.0% of its reports

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