Lethargy after Fluralaner (Bravecto) in dogs

6,278 reports to the FDA describe lethargy in dogs given Fluralaner. That is 9.1% of all reports for this medicine, compared with 11% across reports for all dog medicines.

6,278Reports

71%Marked serious

33%Recovered

11%Died or euthanised

1 daysTypical onset

How soon it started

Same day

1,779 40%

1–2 days

1,376 31%

3–7 days

411 9.2%

1–4 weeks

285 6.4%

Over a month

621 14%

How the animals did

Recovered

1,948 31%

Recovered with lasting effects

101 1.6%

Still unwell when reported

2,754 44%

Died

268 4.3%

Euthanised

429 6.8%

Not known

778 12%

Problems reported at the same time

2,863 46%

2,701 43%

1,463 23%

692 11%

681 11%

648 10%

536 8.5%

488 7.8%

Age of the animals

Under 1 year

639

1–3 years

1,741

4–7 years

1,670

8–11 years

1,439

12+ years

667

About this medicine

Fluralaner kills fleas and ticks for up to 12 weeks (chewable or spot-on).

Products with this ingredient include Bravecto. 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 Fluralaner cause lethargy in dogs?: 6,278 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).

Lethargy with similar medicines

Lethargy after Afoxolaner (NexGard) 6,825 reports · 12% of its reports
Lethargy after Sarolaner (Simparica) 1,852 reports · 11% of its reports
Lethargy after Lotilaner (Credelio) 1,033 reports · 10% of its reports
Lethargy after Afoxolaner + Moxidectin + Pyrantel (NexGard PLUS) 747 reports · 8.1% of its reports
Lethargy after Lotilaner + Moxidectin + Praziquantel + Pyrantel (Credelio Quattro) 396 reports · 13% of its reports

All reported side effects of Fluralaner in dogs · Medicines most reported with lethargy