The worst part of a flea infestation is not what you can see—it’s what you can’t. Microscopic flea eggs, larvae and pupae can permeate your home and keep the flea infestation cycle going. Comfortis kills fleas before they lay eggs and keeps killing fleas for a full month with each dose. Use Comfortis for at least three months to treat a current flea infestation, then continue routine use to prevent a re-infestation on your pet. In a field study conducted in households with existing flea infestations in dogs, flea count reductions of 97.9% were observed one month after the first treatment and 99.9% after three monthly treatments with Comfortis.