Blood problems after Spinosad (Comfortis) in dogs

364 reports to the FDA describe blood problems in dogs given Spinosad. That is 0.6% of all reports for this medicine, compared with 1.8% across reports for all dog medicines, so it is reported less often than average with this medicine.

364Reports

49%Marked serious

13%Recovered

33%Died or euthanised

5 daysTypical onset

How soon it started

Same day

36 25%

1–2 days

28 19%

3–7 days

12 8.3%

1–4 weeks

19 13%

Over a month

50 34%

How the animals did

Recovered

21 5.8%

Recovered with lasting effects

28 7.7%

Still unwell when reported

54 15%

Died

76 21%

Euthanised

44 12%

Not known

141 39%

Problems reported at the same time

191 52%

159 44%

136 37%

126 35%

119 33%

80 22%

79 22%

59 16%

Age of the animals

Under 1 year

1–3 years

4–7 years

111

8–11 years

104

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 blood problems in dogs?: 364 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 5 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).

Blood problems with similar medicines

Blood problems after Lufenuron + Milbemycin Oxime (Sentinel) 184 reports · 0.7% of its reports
Blood problems after Imidacloprid + Moxidectin (Advantage Multi) 88 reports · 0.7% of its reports
Blood problems after Nitenpyram (Capstar) 54 reports · 0.5% of its reports
Blood problems after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 49 reports · 0.5% of its reports
Blood problems after Fipronil + S-methoprene (Frontline Plus) 23 reports · 0.8% of its reports
Blood problems after Flumethrin + Imidacloprid (Seresto) 28 reports · 1.2% of its reports
Blood problems after Fipronil 20 reports · 1.4% of its reports
Blood problems after Lufenuron 27 reports · 2.7% of its reports

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