How quickly will Comfortis® (spinosad) kill fleas?

Spinosad, the active ingredient in Comfortis, began killing fleas in 30 minutes and killed 100% of fleas on dogs and 98% of fleas on cats in just four hours in controlled laboratory studies. Comfortis chewable tablets kill fleas before they can lay eggs.

How long does Comfortis last?

Comfortis has demonstrated full effectiveness for an entire month.

Does seeing fleas on my dog or cat mean the treatment isn’t working?

Comfortis kills fleas before they can lay eggs when used monthly, according to the label directions. If you see fleas on your dog or cat within a month after your pet receives Comfortis, they are most likely new fleas. Because your pet has been treated with Comfortis, these new fleas will be killed before they can produce eggs that contaminate your home. Continued monthly use of Comfortis can prevent any new flea infestations.

Your pet can experience continued exposure to fleas living in the environment. It’s important to treat all animals in the household with an approved flea product to help control the flea population. Learn more about controlling flea infestations in your home.