Capstar is a fast acting tablet that provides flea relief for your dog within 30 minutes of use. Capstar is an orally administered tablet, so there's no odor or messy application on your pet or in your home. A single dose of Capstar should kill the adult fleas on your pet. If your pet get re-infested, it is safe to give another dose as often as once per day. You will literally see fleas falling off your pet. Capstar is safe for puppies and kittens four weeks and older, weighing two pounds or greater, as well as for pregnant or nursing dogs.