Capstar (nitenpyram) is a fast-acting flea tablet for dogs and cats. A single dose of Capstar (nitenpyram) starts killing fleas within 30 minutes and achieves greater than 90% effectiveness against adult fleas within 4 hours for dogs and 6 hours for cats. This oral flea tablet treats flea infestations in dogs, puppies, cats and kittens 2 pounds of body weight or greater and 4 weeks of age or older. Capstar kills adult fleas that may cause flea allergy dermatitis. It is safe to give as often as once a day if your pet gets re-infested with fleas and can be given with or without food.