Itching after Cyphenothrin + Fipronil in dogs

The FDA has received 72 reports of itching in dogs after Cyphenothrin + Fipronil. That is 25% 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.

72Reports

54%Marked serious

65%Recovered

0.0%Died or euthanised

11 daysTypical onset

How soon it started

Same day

17 43%

1–2 days

3 7.5%

3–7 days

0 0.0%

1–4 weeks

5 13%

Over a month

15 38%

How the animals did

Recovered

47 65%

Still unwell when reported

20 28%

Not known

5 6.9%

Problems reported at the same time

Restlessness or agitation

29 40%

Lethargy

12 17%

Breathing problems

12 17%

Anxiety

11 15%

Vocalising

10 14%

Skin redness

8 11%

Application site reaction

8 11%

Loss of appetite

6 8.3%

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).

Questions owners ask

Can Cyphenothrin + Fipronil cause itching in dogs?: 72 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 11 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 Cyphenothrin + Fipronil in dogs · Medicines most reported with itching