Didn't prevent heartworm after Fluralaner (Bravecto) in dogs

The FDA has received 638 reports of didn't prevent heartworm in dogs after Fluralaner. That is 0.9% of all reports for this medicine, compared with 13% across reports for all dog medicines, so it is reported less often than average with this medicine.

638Reports

25%Marked serious

1.3%Recovered

0.8%Died or euthanised

279 daysTypical onset

How soon it started

Same day

3 1.8%

1–2 days

1 0.6%

3–7 days

3 1.8%

1–4 weeks

7 4.1%

Over a month

155 92%

How the animals did

Recovered

6 0.9%

Recovered with lasting effects

2 0.3%

Still unwell when reported

185 29%

Euthanised

5 0.8%

Not known

440 69%

Problems reported at the same time

Drug dose omission

31 4.9%

Didn't work as expected

30 4.7%

27 4.2%

19 3.0%

19 3.0%

14 2.2%

14 2.2%

12 1.9%

Age of the animals

Under 1 year

1–3 years

356

4–7 years

174

8–11 years

12+ years

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 didn't prevent heartworm in dogs?: 638 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 279 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 prevent heartworm with similar medicines

Didn't prevent heartworm after Afoxolaner (NexGard) 831 reports · 1.5% of its reports
Didn't prevent heartworm after Sarolaner (Simparica) 287 reports · 1.7% of its reports
Didn't prevent heartworm after Lotilaner (Credelio) 487 reports · 4.9% of its reports
Didn't prevent heartworm after Afoxolaner + Moxidectin + Pyrantel (NexGard PLUS) 1,168 reports · 13% of its reports
Didn't prevent heartworm after Lotilaner + Moxidectin + Praziquantel + Pyrantel (Credelio Quattro) 126 reports · 4.1% of its reports

All reported side effects of Fluralaner in dogs · Medicines most reported with didn't prevent heartworm