Hair shedding after Spinosad (Comfortis) in dogs

46 reports to the FDA describe hair shedding in dogs given Spinosad. That is 0.1% of all reports for this medicine, compared with 0.1% across reports for all dog medicines.

46Reports

4.3%Marked serious

30%Recovered

2.2%Died or euthanised

1 daysTypical onset

How soon it started

Same day

7 44%

1–2 days

2 13%

3–7 days

1 6.3%

1–4 weeks

2 13%

Over a month

4 25%

How the animals did

Recovered

3 6.5%

Recovered with lasting effects

11 24%

Still unwell when reported

1 2.2%

Died

1 2.2%

Not known

30 65%

Problems reported at the same time

7 15%

7 15%

5 11%

5 11%

4 8.7%

4 8.7%

3 6.5%

3 6.5%

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 hair shedding in dogs?: 46 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 1 day 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).

Hair shedding with similar medicines

Hair shedding after Lufenuron + Milbemycin Oxime (Sentinel) 24 reports · 0.1% of its reports
Hair shedding after Imidacloprid + Moxidectin (Advantage Multi) 20 reports · 0.2% of its reports

All reported side effects of Spinosad in dogs · Medicines most reported with hair shedding