Behaviour change after Imidacloprid + Pyriproxyfen in cats

80 reports to the FDA describe behaviour change in cats given Imidacloprid + Pyriproxyfen. That is 12% 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.

80Reports

46%Marked serious

34%Recovered

3.8%Died or euthanised

14 daysTypical onset

How soon it started

Same day

12 27%

1–2 days

4 8.9%

3–7 days

3 6.7%

1–4 weeks

14 31%

Over a month

12 27%

How the animals did

Recovered

27 34%

Still unwell when reported

11 14%

Died

1 1.3%

Euthanised

2 2.5%

Not known

39 49%

Problems reported at the same time

34 43%

20 25%

16 20%

14 18%

Restlessness or agitation

13 16%

Hiding

12 15%

Loss of appetite

11 14%

Vocalising

10 13%

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).

Questions owners ask

Can Imidacloprid + Pyriproxyfen cause behaviour change in cats?: 80 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 14 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 Flumethrin + Imidacloprid (Seresto) 68 reports · 10% 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 Imidacloprid + Pyriproxyfen in cats · Medicines most reported with behaviour change