Itching after Amitraz + Fipronil + S-methoprene in dogs

The FDA has received 39 reports of itching in dogs after Amitraz + Fipronil + S-methoprene. That is 8.5% 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.

39Reports

85%Marked serious

41%Recovered

2.6%Died or euthanised

31 daysTypical onset

How soon it started

Same day

5 18%

1–2 days

4 14%

3–7 days

0 0.0%

1–4 weeks

5 18%

Over a month

14 50%

How the animals did

Recovered

14 36%

Recovered with lasting effects

2 5.1%

Still unwell when reported

6 15%

Euthanised

1 2.6%

Not known

16 41%

Problems reported at the same time

Application site reaction

17 44%

Lethargy

14 36%

Hair loss

11 28%

Skin redness

6 15%

Restlessness or agitation

6 15%

Skin sore

5 13%

Liver problems

5 13%

Vomiting

4 10%

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 Amitraz + Fipronil + S-methoprene cause itching in dogs?: 39 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).

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 Amitraz + Fipronil + S-methoprene in dogs · Medicines most reported with itching