Weight loss after Spinosad (Comfortis) in dogs

The FDA has received 531 reports of weight loss in dogs after Spinosad. That is 0.9% of all reports for this medicine, compared with 1.7% across reports for all dog medicines, so it is reported less often than average with this medicine.

531Reports

45%Marked serious

28%Recovered

20%Died or euthanised

8 daysTypical onset

How soon it started

Same day

88 34%

1–2 days

28 11%

3–7 days

11 4.3%

1–4 weeks

30 12%

Over a month

100 39%

How the animals did

Recovered

82 15%

Recovered with lasting effects

65 12%

Still unwell when reported

68 13%

Died

63 12%

Euthanised

41 7.7%

Not known

212 40%

Problems reported at the same time

262 49%

221 42%

194 37%

104 20%

97 18%

93 18%

77 15%

55 10%

Age of the animals

Under 1 year

1–3 years

4–7 years

134

8–11 years

146

12+ years

113

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 weight loss in dogs?: 531 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).

Weight loss with similar medicines

Weight loss after Lufenuron + Milbemycin Oxime (Sentinel) 280 reports · 1.1% of its reports
Weight loss after Imidacloprid + Moxidectin (Advantage Multi) 236 reports · 1.8% of its reports
Weight loss after Nitenpyram (Capstar) 89 reports · 0.8% of its reports
Weight loss after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 77 reports · 0.8% of its reports
Weight loss after Fipronil + S-methoprene (Frontline Plus) 29 reports · 1.0% of its reports
Weight loss after Flumethrin + Imidacloprid (Seresto) 57 reports · 2.5% of its reports
Weight loss after Fipronil 28 reports · 2.0% of its reports

All reported side effects of Spinosad in dogs · Medicines most reported with weight loss