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

The FDA has received 676 reports of didn't stop fleas in cats after Fluralaner + Moxidectin. That is 21% 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.

676Reports
23%Marked serious
3.6%Recovered
0.4%Died or euthanised
Same dayTypical onset
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How soon it started

Same day
177 54%
1–2 days
5 1.5%
3–7 days
16 4.9%
1–4 weeks
43 13%
Over a month
88 27%

How the animals did

Recovered
23 3.4%
Recovered with lasting effects
1 0.1%
Still unwell when reported
629 93%
Died
1 0.1%
Euthanised
2 0.3%
Not known
20 3.0%

Problems reported at the same time

Drug administered at inappropriate site
33 4.9%
Drug dose administration interval too short
21 3.1%
Didn't stop worms
17 2.5%
Didn't work as expected
12 1.8%
Didn't stop ticks
10 1.5%
Application site reaction
9 1.3%
Medication error
8 1.2%
Itching
7 1.0%

Age of the animals

Under 1 year
37
1–3 years
178
4–7 years
143
8–11 years
119
12+ years
96

About this medicine

Fluralaner kills fleas and ticks for up to 12 weeks (chewable or spot-on). Moxidectin prevents heartworm disease (monthly topical, or a 6- or 12-month injection for dogs).

Products with this combination include Bravecto Plus. 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 + Moxidectin cause didn't stop fleas in cats?
676 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

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