Didn't stop ticks after Afoxolaner (NexGard) in dogs

8,328 reports to the FDA describe didn't stop ticks in dogs given Afoxolaner. That is 15% of all reports for this medicine, compared with 2.3% across reports for all dog medicines, so it is reported unusually often with this medicine.

8,328Reports

13%Marked serious

9.3%Recovered

0.7%Died or euthanised

27 daysTypical onset

How soon it started

Same day

407 11%

1–2 days

245 6.5%

3–7 days

287 7.7%

1–4 weeks

1,076 29%

Over a month

1,736 46%

How the animals did

Recovered

755 9.1%

Recovered with lasting effects

21 0.3%

Still unwell when reported

1,247 15%

Died

29 0.3%

Euthanised

31 0.4%

Not known

6,245 75%

Problems reported at the same time

Didn't work as expected

4,644 56%

963 12%

359 4.3%

167 2.0%

146 1.8%

101 1.2%

85 1.0%

73 0.9%

Age of the animals

Under 1 year

738

1–3 years

2,775

4–7 years

1,866

8–11 years

1,006

12+ years

285

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 didn't stop ticks in dogs?: 8,328 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 27 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).

Didn't stop ticks with similar medicines

Didn't stop ticks after Fluralaner (Bravecto) 6,711 reports · 9.8% of its reports
Didn't stop ticks after Sarolaner (Simparica) 2,073 reports · 12% of its reports
Didn't stop ticks after Lotilaner (Credelio) 843 reports · 8.5% of its reports
Didn't stop ticks after Afoxolaner + Moxidectin + Pyrantel (NexGard PLUS) 273 reports · 2.9% of its reports
Didn't stop ticks after Lotilaner + Moxidectin + Praziquantel + Pyrantel (Credelio Quattro) 53 reports · 1.7% of its reports

All reported side effects of Afoxolaner in dogs · Medicines most reported with didn't stop ticks