Loose stool after Afoxolaner (NexGard) in dogs

703 reports to the FDA describe loose stool in dogs given Afoxolaner. That is 1.2% of all reports for this medicine, compared with 0.9% across reports for all dog medicines.

703Reports

43%Marked serious

36%Recovered

3.8%Died or euthanised

2 daysTypical onset

How soon it started

Same day

172 30%

1–2 days

144 25%

3–7 days

51 8.8%

1–4 weeks

64 11%

Over a month

147 25%

How the animals did

Recovered

249 35%

Recovered with lasting effects

1 0.1%

Still unwell when reported

76 11%

Died

10 1.4%

Euthanised

17 2.4%

Not known

350 50%

Problems reported at the same time

269 38%

184 26%

171 24%

69 9.8%

67 9.5%

41 5.8%

38 5.4%

38 5.4%

Age of the animals

Under 1 year

128

1–3 years

186

4–7 years

159

8–11 years

129

12+ years

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 loose stool in dogs?: 703 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).

Loose stool with similar medicines

Loose stool after Fluralaner (Bravecto) 614 reports · 0.9% of its reports
Loose stool after Sarolaner (Simparica) 178 reports · 1.1% of its reports
Loose stool after Lotilaner (Credelio) 159 reports · 1.6% of its reports
Loose stool after Afoxolaner + Moxidectin + Pyrantel (NexGard PLUS) 89 reports · 1.0% of its reports
Loose stool after Lotilaner + Moxidectin + Praziquantel + Pyrantel (Credelio Quattro) 62 reports · 2.0% of its reports

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