Weakness after Sarolaner (Simparica) in dogs

The FDA has received 280 reports of weakness in dogs after Sarolaner. That is 1.7% of all reports for this medicine, compared with 1.4% across reports for all dog medicines.

280Reports
55%Marked serious
21%Recovered
13%Died or euthanised
1 daysTypical onset
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How soon it started

Same day
106 41%
1–2 days
78 30%
3–7 days
15 5.8%
1–4 weeks
30 12%
Over a month
29 11%

How the animals did

Recovered
59 21%
Still unwell when reported
134 48%
Died
13 4.6%
Euthanised
24 8.6%
Not known
50 18%

Problems reported at the same time

Age of the animals

Under 1 year
11
1–3 years
45
4–7 years
47
8–11 years
79
12+ years
86

About this medicine

Sarolaner kills fleas, ticks and some mites; monthly.

Products with this ingredient include Simparica. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

In 2018 the FDA alerted owners and vets that isoxazoline products have been associated with neurologic reactions such as muscle tremors, wobbliness (ataxia) and seizures, including in animals with no history of them.

Questions owners ask

Can Sarolaner cause weakness in dogs?
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 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).

Weakness with similar medicines

All reported side effects of Sarolaner in dogs · Medicines most reported with weakness