Tachycardia after Spinosad (Comfortis) in dogs

126 reports to the FDA describe tachycardia in dogs given Spinosad. That is 0.2% of all reports for this medicine, compared with 0.5% across reports for all dog medicines, so it is reported less often than average with this medicine.

126Reports
36%Marked serious
25%Recovered
23%Died or euthanised
5 daysTypical onset
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How soon it started

Same day
17 35%
1–2 days
5 10%
3–7 days
4 8.2%
1–4 weeks
4 8.2%
Over a month
19 39%

How the animals did

Recovered
21 17%
Recovered with lasting effects
11 8.7%
Still unwell when reported
1 0.8%
Died
17 13%
Euthanised
12 9.5%
Not known
64 51%

Problems reported at the same time

Age of the animals

Under 1 year
9
1–3 years
44
4–7 years
27
8–11 years
28
12+ years
15

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 tachycardia in dogs?
126 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).

Tachycardia with similar medicines

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