Spinosad (Comfortis) side effects in cats
11,584 reports sent to the FDA between 2007 and 2026 involve Spinosad in cats. The most reported problems were vomiting, lethargy, loss of appetite. 6.7% were marked serious, and where it was recorded, signs eased after stopping the medicine in 100% of cases.
About this medicine
Spinosad kills fleas; monthly chewable.
Products with this ingredient include Comfortis. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.
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 (10,230 reports).
How the animals did
Breeds named most often
Popular breeds appear more often because there are more of them.
- Domestic Shorthair 6,360 reports
- Domestic Longhair 1,198 reports
- Domestic Mediumhair 776 reports
- Domestic 556 reports
- Siamese 288 reports
- Maine Coon 253 reports
- Persian 168 reports
- Himalayan 88 reports
- Ragdoll 73 reports
- American Shorthair 55 reports