Didn't stop fleas after Spinosad (Comfortis) in dogs

13,280 reports to the FDA describe didn't stop fleas in dogs given Spinosad. That is 23% of all reports for this medicine, compared with 6.2% across reports for all dog medicines, so it is reported unusually often with this medicine.

13,280Reports

1.9%Marked serious

11%Recovered

0.2%Died or euthanised

20 daysTypical onset

How soon it started

Same day

954 18%

1–2 days

220 4.3%

3–7 days

432 8.4%

1–4 weeks

1,606 31%

Over a month

1,958 38%

How the animals did

Recovered

669 5.0%

Recovered with lasting effects

817 6.2%

Still unwell when reported

213 1.6%

Died

21 0.2%

Euthanised

11 0.1%

Not known

11,549 87%

Problems reported at the same time

Itching

1,475 11%

Didn't work as expected

1,402 11%

903 6.8%

480 3.6%

415 3.1%

340 2.6%

273 2.1%

Drug dose administration interval too short

211 1.6%

Age of the animals

Under 1 year

908

1–3 years

3,465

4–7 years

3,474

8–11 years

2,104

12+ years

957

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 didn't stop fleas in dogs?: 13,280 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 20 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).

Didn't stop fleas with similar medicines

Didn't stop fleas after Lufenuron + Milbemycin Oxime (Sentinel) 977 reports · 3.8% of its reports
Didn't stop fleas after Imidacloprid + Moxidectin (Advantage Multi) 1,444 reports · 11% of its reports
Didn't stop fleas after Nitenpyram (Capstar) 6,142 reports · 57% of its reports
Didn't stop fleas after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 498 reports · 5.0% of its reports
Didn't stop fleas after Fipronil + S-methoprene (Frontline Plus) 576 reports · 19% of its reports
Didn't stop fleas after Flumethrin + Imidacloprid (Seresto) 882 reports · 39% of its reports
Didn't stop fleas after Imidacloprid 1,054 reports · 55% of its reports
Didn't stop fleas after Fipronil 394 reports · 28% of its reports
Didn't stop fleas after Lufenuron 44 reports · 4.3% of its reports
Didn't stop fleas after Imidacloprid + Permethrin + Pyriproxyfen 219 reports · 30% of its reports

All reported side effects of Spinosad in dogs · Medicines most reported with didn't stop fleas