Afoxolaner (NexGard) side effects in cats
80 reports sent to the FDA between 2014 and 2026 involve Afoxolaner in cats. The most reported problems were vomiting, loss of appetite, lethargy. 31% were marked serious.
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 cat 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 (71 reports).
How the animals did
Breeds named most often
Popular breeds appear more often because there are more of them.
- Domestic Shorthair 42 reports
- Domestic Longhair 6 reports
- Domestic Mediumhair 5 reports
- Maine Coon 2 reports
- Siamese 1 reports
- European 1 reports
- Russian 1 reports