There are accounts of cats having side effects that included lethargy and violent itching as the medication was taking effect. While most cats can tolerate the active ingredient nitenpyram, there’s ...

Cat flea medicine. The pill nitenpyram (Capstar) kills adult fleas on your cat within 30 minutes. It doesn't have any lasting effects, though. Spinosad (Comfortis) is a fast-acting chewable that ...

The active ingredient in Capstar, nitenpyram, works within 30 minutes and kills more than 90% of adult fleas in as little as four hours. It only protects for 24 hours, but it is safe to give daily ...

The active ingredient in Capstar, nitenpyram, works within 30 minutes and kills more than 90% of adult fleas in as little as six hours. Capstar only protects against fleas for 24 hours ...