Behaviour change after Spinosad (Comfortis) in cats

The FDA has received 359 reports of behaviour change in cats after Spinosad. That is 3.1% of all reports for this medicine, compared with 5.4% across reports for all cat medicines, so it is reported less often than average with this medicine.

359Reports

26%Marked serious

46%Recovered

13%Died or euthanised

Same dayTypical onset

How soon it started

Same day

195 61%

1–2 days

41 13%

3–7 days

15 4.7%

1–4 weeks

22 6.9%

Over a month

48 15%

How the animals did

Recovered

131 36%

Recovered with lasting effects

35 9.7%

Still unwell when reported

38 11%

Died

30 8.4%

Euthanised

16 4.5%

Not known

109 30%

Problems reported at the same time

123 34%

105 29%

74 21%

47 13%

47 13%

44 12%

Restlessness or agitation

40 11%

Vocalising

33 9.2%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Spinosad kills fleas; monthly chewable.

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

Questions owners ask

Can Spinosad cause behaviour change in cats?: 359 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 the same day 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 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 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 Spinosad in cats · Medicines most reported with behaviour change