Weakness after Afoxolaner (NexGard) in dogs

452 reports to the FDA describe weakness in dogs given Afoxolaner. That is 0.8% of all reports for this medicine, compared with 1.4% across reports for all dog medicines, so it is reported less often than average with this medicine.

452Reports
53%Marked serious
26%Recovered
15%Died or euthanised
2 daysTypical onset
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How soon it started

Same day
110 29%
1–2 days
96 25%
3–7 days
45 12%
1–4 weeks
43 11%
Over a month
89 23%

How the animals did

Recovered
115 25%
Recovered with lasting effects
2 0.4%
Still unwell when reported
66 15%
Died
35 7.7%
Euthanised
33 7.3%
Not known
201 44%

Problems reported at the same time

Age of the animals

Under 1 year
78
1–3 years
82
4–7 years
84
8–11 years
111
12+ years
86

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 weakness in dogs?
452 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 2 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).

Weakness with similar medicines

All reported side effects of Afoxolaner in dogs · Medicines most reported with weakness