Liver problems after Spinosad (Comfortis) in dogs

The FDA has received 955 reports of liver problems in dogs after Spinosad. That is 1.7% of all reports for this medicine, compared with 4.6% across reports for all dog medicines, so it is reported less often than average with this medicine.

955Reports

42%Marked serious

23%Recovered

18%Died or euthanised

8 daysTypical onset

How soon it started

Same day

108 30%

1–2 days

46 13%

3–7 days

28 7.7%

1–4 weeks

35 9.6%

Over a month

148 41%

How the animals did

Recovered

79 8.3%

Recovered with lasting effects

143 15%

Still unwell when reported

106 11%

Died

115 12%

Euthanised

61 6.4%

Not known

451 47%

Problems reported at the same time

390 41%

349 37%

295 31%

183 19%

175 18%

144 15%

126 13%

118 12%

Age of the animals

Under 1 year

1–3 years

175

4–7 years

240

8–11 years

304

12+ years

149

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 dogs?: 955 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 8 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

Liver problems after Lufenuron + Milbemycin Oxime (Sentinel) 414 reports · 1.6% of its reports
Liver problems after Imidacloprid + Moxidectin (Advantage Multi) 197 reports · 1.5% of its reports
Liver problems after Nitenpyram (Capstar) 87 reports · 0.8% of its reports
Liver problems after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 132 reports · 1.3% of its reports
Liver problems after Fipronil + S-methoprene (Frontline Plus) 68 reports · 2.3% of its reports
Liver problems after Flumethrin + Imidacloprid (Seresto) 47 reports · 2.1% of its reports
Liver problems after Fipronil 53 reports · 3.8% of its reports
Liver problems after Lufenuron 53 reports · 5.2% of its reports
Liver problems after Imidacloprid + Permethrin + Pyriproxyfen 21 reports · 2.8% of its reports
Liver problems after Imidacloprid + Permethrin 24 reports · 5.1% of its reports

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