Itching after Fipronil + Pyriproxyfen + S-methoprene in dogs

The FDA has received 46 reports of itching in dogs after Fipronil + Pyriproxyfen + S-methoprene. That is 11% of all reports for this medicine, compared with 4.3% across reports for all dog medicines, so it is reported unusually often with this medicine.

46Reports

28%Marked serious

35%Recovered

0.0%Died or euthanised

5 daysTypical onset

How soon it started

Same day

5 19%

1–2 days

5 19%

3–7 days

6 22%

1–4 weeks

5 19%

Over a month

6 22%

How the animals did

Recovered

16 35%

Still unwell when reported

2 4.3%

Not known

28 61%

Problems reported at the same time

Lethargy

8 17%

Application site reaction

6 13%

Skin disorders

4 8.7%

Vomiting

4 8.7%

Loss of appetite

3 6.5%

Tremors

3 6.5%

Skin rash or irritation

3 6.5%

Skin redness

3 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).

Questions owners ask

Can Fipronil + Pyriproxyfen + S-methoprene cause itching in dogs?: 46 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 5 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).

Itching with similar medicines

Itching after Spinosad (Comfortis) 3,874 reports · 6.8% of its reports
Itching after Lufenuron + Milbemycin Oxime (Sentinel) 1,223 reports · 4.7% of its reports
Itching after Imidacloprid + Moxidectin (Advantage Multi) 2,227 reports · 17% of its reports
Itching after Nitenpyram (Capstar) 1,450 reports · 13% of its reports
Itching after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 281 reports · 2.8% of its reports
Itching after Fipronil + S-methoprene (Frontline Plus) 330 reports · 11% of its reports
Itching after Flumethrin + Imidacloprid (Seresto) 610 reports · 27% of its reports
Itching after Imidacloprid 297 reports · 16% of its reports
Itching after Fipronil 138 reports · 9.8% of its reports
Itching after Lufenuron 178 reports · 17% of its reports

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