Lethargy after Afoxolaner + Moxidectin + Pyrantel (NexGard PLUS) in dogs

747 reports to the FDA describe lethargy in dogs given Afoxolaner + Moxidectin + Pyrantel. That is 8.1% of all reports for this medicine, compared with 11% across reports for all dog medicines.

747Reports

18%Marked serious

43%Recovered

5.2%Died or euthanised

1 daysTypical onset

How soon it started

Same day

353 50%

1–2 days

226 32%

3–7 days

51 7.2%

1–4 weeks

44 6.2%

Over a month

36 5.1%

How the animals did

Recovered

322 43%

Still unwell when reported

92 12%

Died

18 2.4%

Euthanised

21 2.8%

Not known

294 39%

Problems reported at the same time

297 40%

267 36%

190 25%

94 13%

70 9.4%

56 7.5%

53 7.1%

47 6.3%

Age of the animals

Under 1 year

150

1–3 years

239

4–7 years

185

8–11 years

118

12+ years

About this medicine

Afoxolaner kills fleas and ticks; given as a monthly chewable. Moxidectin prevents heartworm disease (monthly topical, or a 6- or 12-month injection for dogs). Pyrantel treats roundworms and hookworms.

Products with this combination include NexGard PLUS. 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 + Moxidectin + Pyrantel cause lethargy in dogs?: 747 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).

Lethargy with similar medicines

Lethargy after Fluralaner (Bravecto) 6,278 reports · 9.1% of its reports
Lethargy after Afoxolaner (NexGard) 6,825 reports · 12% of its reports
Lethargy after Sarolaner (Simparica) 1,852 reports · 11% of its reports
Lethargy after Lotilaner (Credelio) 1,033 reports · 10% of its reports
Lethargy after Lotilaner + Moxidectin + Praziquantel + Pyrantel (Credelio Quattro) 396 reports · 13% of its reports

All reported side effects of Afoxolaner + Moxidectin + Pyrantel in dogs · Medicines most reported with lethargy