Diarrhea after Afoxolaner (NexGard) in dogs

The FDA has received 6,014 reports of diarrhea in dogs after Afoxolaner. That is 11% of all reports for this medicine, compared with 8.4% across reports for all dog medicines.

6,014Reports

43%Marked serious

39%Recovered

3.8%Died or euthanised

1 daysTypical onset

How soon it started

Same day

1,810 35%

1–2 days

1,390 27%

3–7 days

390 7.6%

1–4 weeks

463 9.1%

Over a month

1,054 21%

How the animals did

Recovered

2,307 38%

Recovered with lasting effects

13 0.2%

Still unwell when reported

467 7.8%

Died

132 2.2%

Euthanised

94 1.6%

Not known

3,001 50%

Problems reported at the same time

3,144 52%

1,549 26%

1,283 21%

379 6.3%

246 4.1%

229 3.8%

229 3.8%

212 3.5%

Age of the animals

Under 1 year

1,323

1–3 years

1,517

4–7 years

1,292

8–11 years

1,021

12+ years

477

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 diarrhea in dogs?: 6,014 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 1 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).

Diarrhea with similar medicines

Diarrhea after Fluralaner (Bravecto) 5,046 reports · 7.3% of its reports
Diarrhea after Sarolaner (Simparica) 1,487 reports · 8.9% of its reports
Diarrhea after Lotilaner (Credelio) 1,243 reports · 12% of its reports
Diarrhea after Afoxolaner + Moxidectin + Pyrantel (NexGard PLUS) 938 reports · 10% of its reports
Diarrhea after Lotilaner + Moxidectin + Praziquantel + Pyrantel (Credelio Quattro) 680 reports · 22% of its reports

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