Application site reaction after Fipronil + S-methoprene (Frontline Plus) in dogs

185 reports to the FDA describe application site reaction in dogs given Fipronil + S-methoprene. That is 6.3% of all reports for this medicine, compared with 0.4% across reports for all dog medicines, so it is reported unusually often with this medicine.

185Reports

74%Marked serious

29%Recovered

0.5%Died or euthanised

68 daysTypical onset

How soon it started

Same day

7 8.5%

1–2 days

9 11%

3–7 days

7 8.5%

1–4 weeks

7 8.5%

Over a month

52 63%

How the animals did

Recovered

53 29%

Still unwell when reported

14 7.6%

Died

1 0.5%

Not known

117 63%

Problems reported at the same time

Hair loss

42 23%

Itching

27 15%

Hair coat discolouration

12 6.5%

Lethargy

11 5.9%

Behaviour change

10 5.4%

Vomiting

9 4.9%

Restlessness or agitation

9 4.9%

Skin redness

8 4.3%

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 application site reaction in dogs?: 185 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 68 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).

Application site reaction with similar medicines

Application site reaction after Imidacloprid + Moxidectin (Advantage Multi) 658 reports · 5.0% of its reports
Application site reaction after Flumethrin + Imidacloprid (Seresto) 123 reports · 5.4% of its reports
Application site reaction after Imidacloprid + Permethrin + Pyriproxyfen 40 reports · 5.4% of its reports
Application site reaction after Cyphenothrin + Fipronil + S-methoprene 83 reports · 13% of its reports
Application site reaction after Amitraz + Fipronil + S-methoprene 73 reports · 16% of its reports
Application site reaction after Fipronil + Pyriproxyfen + S-methoprene 24 reports · 5.6% of its reports

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