Liver problems after Spinosad (Comfortis) in cats

97 reports to the FDA describe liver problems in cats given Spinosad. That is 0.8% of all reports for this medicine, compared with 2.8% across reports for all cat medicines, so it is reported less often than average with this medicine.

97Reports
84%Marked serious
20%Recovered
51%Died or euthanised
2 daysTypical onset
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How soon it started

Same day
29 38%
1–2 days
10 13%
3–7 days
12 16%
1–4 weeks
8 10%
Over a month
18 23%

How the animals did

Recovered
10 10%
Recovered with lasting effects
9 9.3%
Still unwell when reported
11 11%
Died
35 36%
Euthanised
14 14%
Not known
18 19%

Problems reported at the same time

Age of the animals

Under 1 year
3
1–3 years
16
4–7 years
21
8–11 years
27
12+ years
28

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 liver problems in cats?
97 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 2 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).

Liver problems with similar medicines

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