Itching after Flumethrin + Imidacloprid (Seresto) in cats

210 reports to the FDA describe itching in cats given Flumethrin + Imidacloprid. That is 31% of all reports for this medicine, compared with 8.9% across reports for all cat medicines, so it is reported unusually often with this medicine.

210Reports

47%Marked serious

20%Recovered

2.9%Died or euthanised

21 daysTypical onset

How soon it started

Same day

15 10%

1–2 days

13 9.0%

3–7 days

21 14%

1–4 weeks

35 24%

Over a month

61 42%

How the animals did

Recovered

42 20%

Still unwell when reported

35 17%

Died

2 1.0%

Euthanised

4 1.9%

Not known

127 60%

Problems reported at the same time

Application site reaction

86 41%

76 36%

75 36%

33 16%

28 13%

Skin rash or irritation

21 10%

Vomiting

17 8.1%

Loss of appetite

15 7.1%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Imidacloprid kills fleas (spot-on or collar).

Products with this combination include Seresto. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

Questions owners ask

Can Flumethrin + Imidacloprid cause itching in cats?: 210 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 21 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) 439 reports · 3.8% of its reports
Itching after Nitenpyram (Capstar) 1,904 reports · 22% of its reports
Itching after Imidacloprid + Moxidectin (Advantage Multi) 1,531 reports · 19% of its reports
Itching after Lufenuron 84 reports · 7.6% of its reports
Itching after Imidacloprid + Pyriproxyfen 222 reports · 34% of its reports
Itching after Fipronil 63 reports · 13% of its reports
Itching after Fipronil + S-methoprene (Frontline Plus) 68 reports · 19% of its reports
Itching after Imidacloprid 42 reports · 17% of its reports

All reported side effects of Flumethrin + Imidacloprid in cats · Medicines most reported with itching