Didn't stop fleas after Sarolaner (Simparica) in dogs

1,139 reports to the FDA describe didn't stop fleas in dogs given Sarolaner. That is 6.8% of all reports for this medicine, compared with 6.2% across reports for all dog medicines.

1,139Reports

7.1%Marked serious

1.1%Recovered

0.2%Died or euthanised

18 daysTypical onset

How soon it started

Same day

201 21%

1–2 days

39 4.0%

3–7 days

83 8.5%

1–4 weeks

285 29%

Over a month

366 38%

How the animals did

Recovered

12 1.1%

Still unwell when reported

342 30%

Died

1 0.1%

Euthanised

1 0.1%

Not known

783 69%

Problems reported at the same time

Itching

32 2.8%

Didn't stop ticks

31 2.7%

Drug dose administration interval too short

25 2.2%

Vomiting

18 1.6%

Didn't work as expected

13 1.1%

Underdose

13 1.1%

Hair loss

11 1.0%

Didn't stop worms

11 1.0%

Age of the animals

Under 1 year

1–3 years

319

4–7 years

276

8–11 years

179

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 stop fleas in dogs?: 1,139 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 18 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 stop fleas with similar medicines

Didn't stop fleas after Fluralaner (Bravecto) 16,499 reports · 24% of its reports
Didn't stop fleas after Afoxolaner (NexGard) 5,900 reports · 10% of its reports
Didn't stop fleas after Lotilaner (Credelio) 613 reports · 6.2% of its reports
Didn't stop fleas after Afoxolaner + Moxidectin + Pyrantel (NexGard PLUS) 372 reports · 4.0% of its reports
Didn't stop fleas after Lotilaner + Moxidectin + Praziquantel + Pyrantel (Credelio Quattro) 84 reports · 2.7% of its reports

All reported side effects of Sarolaner in dogs · Medicines most reported with didn't stop fleas