Increased heart rate after Spinosad (Comfortis) in cats

23 reports to the FDA describe increased heart rate in cats given Spinosad. That is 0.2% of all reports for this medicine, compared with 0.3% across reports for all cat medicines.

23Reports

74%Marked serious

52%Recovered

13%Died or euthanised

Same dayTypical onset

How soon it started

Same day

16 73%

1–2 days

1 4.5%

3–7 days

1 4.5%

1–4 weeks

0 0.0%

Over a month

4 18%

How the animals did

Recovered

9 39%

Recovered with lasting effects

3 13%

Still unwell when reported

2 8.7%

Died

3 13%

Not known

6 26%

Problems reported at the same time

Breathing problems

15 65%

Restlessness or agitation

9 39%

Itching

5 22%

Increased respiratory rate

5 22%

5 22%

4 17%

4 17%

3 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 increased heart rate in cats?: 23 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 the same 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).

Increased heart rate with similar medicines

Increased heart rate after Nitenpyram (Capstar) 136 reports · 1.6% of its reports

All reported side effects of Spinosad in cats · Medicines most reported with increased heart rate