Dehydration after Spinosad (Comfortis) in cats

The FDA has received 81 reports of dehydration in cats after Spinosad. That is 0.7% of all reports for this medicine, compared with 2.0% across reports for all cat medicines, so it is reported less often than average with this medicine.

81Reports

72%Marked serious

28%Recovered

30%Died or euthanised

3 daysTypical onset

How soon it started

Same day

25 36%

1–2 days

10 14%

3–7 days

13 19%

1–4 weeks

6 8.6%

Over a month

16 23%

How the animals did

Recovered

17 21%

Recovered with lasting effects

6 7.4%

Still unwell when reported

17 21%

Died

14 17%

Euthanised

10 12%

Not known

17 21%

Problems reported at the same time

57 70%

50 62%

39 48%

24 30%

24 30%

21 26%

20 25%

18 22%

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 dehydration in cats?: 81 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 3 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).

Dehydration with similar medicines

Dehydration after Nitenpyram (Capstar) 49 reports · 0.6% of its reports
Dehydration after Imidacloprid + Moxidectin (Advantage Multi) 72 reports · 0.9% of its reports
Dehydration after Lufenuron 31 reports · 2.8% of its reports

All reported side effects of Spinosad in cats · Medicines most reported with dehydration