Didn't stop fleas after Fluralaner (Bravecto) in cats

The FDA has received 3,311 reports of didn't stop fleas in cats after Fluralaner. That is 31% of all reports for this medicine, compared with 8.4% across reports for all cat medicines, so it is reported unusually often with this medicine.

3,311Reports

33%Marked serious

2.1%Recovered

0.2%Died or euthanised

Same dayTypical onset

How soon it started

Same day

995 59%

1–2 days

46 2.7%

3–7 days

47 2.8%

1–4 weeks

176 10%

Over a month

418 25%

How the animals did

Recovered

65 2.0%

Recovered with lasting effects

4 0.1%

Still unwell when reported

3,073 93%

Died

3 0.1%

Euthanised

2 0.1%

Not known

164 5.0%

Problems reported at the same time

Drug administered at inappropriate site

317 9.6%

Didn't work as expected

110 3.3%

Hair loss

61 1.8%

Overdose

58 1.8%

Drug dose administration interval too short

54 1.6%

Itching

52 1.6%

Application site reaction

51 1.5%

Underdose

48 1.4%

Age of the animals

Under 1 year

155

1–3 years

796

4–7 years

759

8–11 years

523

12+ years

520

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 stop fleas in cats?: 3,311 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 the same 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).

Didn't stop fleas with similar medicines

Didn't stop fleas after Sarolaner + Selamectin (Revolution Plus) 725 reports · 8.8% of its reports
Didn't stop fleas after Fluralaner + Moxidectin (Bravecto Plus) 676 reports · 21% of its reports
Didn't stop fleas after Lotilaner (Credelio) 147 reports · 16% of its reports

All reported side effects of Fluralaner in cats · Medicines most reported with didn't stop fleas