Musculoskeletal pain after Spinosad (Comfortis) in dogs

The FDA has received 86 reports of musculoskeletal pain in dogs after Spinosad. That is 0.2% of all reports for this medicine, compared with 0.2% across reports for all dog medicines.

86Reports

36%Marked serious

27%Recovered

16%Died or euthanised

18 daysTypical onset

How soon it started

Same day

7 21%

1–2 days

2 5.9%

3–7 days

1 2.9%

1–4 weeks

10 29%

Over a month

14 41%

How the animals did

Recovered

13 15%

Recovered with lasting effects

10 12%

Still unwell when reported

6 7.0%

Died

5 5.8%

Euthanised

9 10%

Not known

43 50%

Problems reported at the same time

40 47%

32 37%

15 17%

14 16%

13 15%

12 14%

12 14%

11 13%

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 musculoskeletal pain in dogs?: 86 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 18 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).

Musculoskeletal pain with similar medicines

Musculoskeletal pain after Lufenuron + Milbemycin Oxime (Sentinel) 40 reports · 0.2% of its reports
Musculoskeletal pain after Imidacloprid + Moxidectin (Advantage Multi) 22 reports · 0.2% of its reports

All reported side effects of Spinosad in dogs · Medicines most reported with musculoskeletal pain