Didn't work as expected after Sarolaner (Simparica) in dogs

The FDA has received 1,487 reports of didn't work as expected in dogs after Sarolaner. That is 8.9% of all reports for this medicine, compared with 13% across reports for all dog medicines.

1,487Reports

43%Marked serious

3.3%Recovered

1.1%Died or euthanised

155 daysTypical onset

How soon it started

Same day

80 15%

1–2 days

12 2.3%

3–7 days

9 1.7%

1–4 weeks

50 9.4%

Over a month

381 72%

How the animals did

Recovered

47 3.2%

Recovered with lasting effects

2 0.1%

Still unwell when reported

1,141 77%

Died

8 0.5%

Euthanised

9 0.6%

Not known

280 19%

Problems reported at the same time

617 41%

95 6.4%

66 4.4%

29 2.0%

21 1.4%

21 1.4%

20 1.3%

17 1.1%

Age of the animals

Under 1 year

1–3 years

430

4–7 years

511

8–11 years

315

12+ years

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 didn't work as expected in dogs?: 1,487 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 155 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 work as expected with similar medicines

Didn't work as expected after Fluralaner (Bravecto) 5,946 reports · 8.6% of its reports
Didn't work as expected after Afoxolaner (NexGard) 8,625 reports · 15% of its reports
Didn't work as expected after Lotilaner (Credelio) 1,497 reports · 15% of its reports
Didn't work as expected after Afoxolaner + Moxidectin + Pyrantel (NexGard PLUS) 1,527 reports · 16% of its reports
Didn't work as expected after Lotilaner + Moxidectin + Praziquantel + Pyrantel (Credelio Quattro) 292 reports · 9.5% of its reports

All reported side effects of Sarolaner in dogs · Medicines most reported with didn't work as expected