Afoxolaner (NexGard) side effects in dogs
57,082 reports sent to the FDA between 2013 and 2026 involve Afoxolaner in dogs. The most reported problems were vomiting, lethargy, itching. 35% were marked serious, and where it was recorded, signs eased after stopping the medicine in 71% of cases.
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.
Most reported side effects
Share = percentage of this medicine's reports that mention the problem. One report can list several problems.
Reports that it didn't work
Some reports are about the medicine not working (for example a dog still getting fleas or heartworm), not about a side effect.
How soon problems started
Time from the first dose to the first sign, where both dates were reported (41,908 reports).
How the animals did
Breeds named most often
Popular breeds appear more often because there are more of them.
- Labrador Retriever 3,953 reports
- Golden Retriever 2,327 reports
- German Shepherd Dog 1,785 reports
- Shih Tzu 1,610 reports
- Yorkshire Terrier 1,527 reports
- Chihuahua 1,281 reports
- Australian Shepherd Dog 1,026 reports
- Pit Bull 854 reports
- Beagle 760 reports
- Dachshund 699 reports