Liver problems after Afoxolaner (NexGard) in dogs

1,408 reports to the FDA describe liver problems in dogs given Afoxolaner. That is 2.5% of all reports for this medicine, compared with 4.6% across reports for all dog medicines, so it is reported less often than average with this medicine.

1,408Reports

62%Marked serious

16%Recovered

17%Died or euthanised

5 daysTypical onset

How soon it started

Same day

246 23%

1–2 days

238 22%

3–7 days

120 11%

1–4 weeks

174 16%

Over a month

301 28%

How the animals did

Recovered

215 15%

Recovered with lasting effects

12 0.9%

Still unwell when reported

277 20%

Died

102 7.2%

Euthanised

142 10%

Not known

660 47%

Problems reported at the same time

537 38%

478 34%

475 34%

275 20%

246 17%

246 17%

218 15%

175 12%

Age of the animals

Under 1 year

139

1–3 years

226

4–7 years

364

8–11 years

401

12+ years

237

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 liver problems in dogs?: 1,408 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 5 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).

Liver problems with similar medicines

Liver problems after Fluralaner (Bravecto) 1,685 reports · 2.5% of its reports
Liver problems after Sarolaner (Simparica) 397 reports · 2.4% of its reports
Liver problems after Lotilaner (Credelio) 220 reports · 2.2% of its reports
Liver problems after Afoxolaner + Moxidectin + Pyrantel (NexGard PLUS) 172 reports · 1.9% of its reports
Liver problems after Lotilaner + Moxidectin + Praziquantel + Pyrantel (Credelio Quattro) 76 reports · 2.5% of its reports

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