Behaviour change after Flumethrin + Imidacloprid (Seresto) in cats

68 reports to the FDA describe behaviour change in cats given Flumethrin + Imidacloprid. That is 10% of all reports for this medicine, compared with 5.4% across reports for all cat medicines, so it is reported unusually often with this medicine.

68Reports

56%Marked serious

32%Recovered

7.4%Died or euthanised

17 daysTypical onset

How soon it started

Same day

6 14%

1–2 days

1 2.3%

3–7 days

5 12%

1–4 weeks

16 37%

Over a month

15 35%

How the animals did

Recovered

22 32%

Still unwell when reported

7 10%

Died

2 2.9%

Euthanised

3 4.4%

Not known

34 50%

Problems reported at the same time

28 41%

21 31%

17 25%

16 24%

11 16%

11 16%

Skin rash or irritation

10 15%

Hiding

10 15%

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 behaviour change in cats?: 68 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 17 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).

Behaviour change with similar medicines

Behaviour change after Spinosad (Comfortis) 359 reports · 3.1% of its reports
Behaviour change after Nitenpyram (Capstar) 564 reports · 6.5% of its reports
Behaviour change after Imidacloprid + Moxidectin (Advantage Multi) 1,057 reports · 13% of its reports
Behaviour change after Lufenuron 24 reports · 2.2% of its reports
Behaviour change after Imidacloprid + Pyriproxyfen 80 reports · 12% of its reports
Behaviour change after Fipronil + S-methoprene (Frontline Plus) 23 reports · 6.3% of its reports
Behaviour change after Imidacloprid 26 reports · 10% of its reports

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