Foaming at the mouth after Afoxolaner (NexGard) in dogs

The FDA has received 325 reports of foaming at the mouth in dogs after Afoxolaner. That is 0.6% of all reports for this medicine, compared with 0.2% across reports for all dog medicines, so it is reported unusually often with this medicine.

325Reports
63%Marked serious
37%Recovered
12%Died or euthanised
3 daysTypical onset
SponsoredWorried about your pet? Ask a veterinarian online, 24/7

How soon it started

Same day
79 28%
1–2 days
55 20%
3–7 days
41 15%
1–4 weeks
55 20%
Over a month
52 18%

How the animals did

Recovered
121 37%
Still unwell when reported
36 11%
Died
23 7.1%
Euthanised
15 4.6%
Not known
130 40%

Problems reported at the same time

Age of the animals

Under 1 year
61
1–3 years
112
4–7 years
77
8–11 years
47
12+ years
24

About this medicine

Afoxolaner kills fleas and ticks; given as a monthly chewable.

Products with this ingredient include NexGard. 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 Afoxolaner cause foaming at the mouth in dogs?
325 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 3 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).

Foaming at the mouth with similar medicines

All reported side effects of Afoxolaner in dogs · Medicines most reported with foaming at the mouth