Kitten owners may de-flea a kitten as early as 4 weeks of age if using Capstar, an oral medication for killing fleas. Topical medications cannot be applied until the kitten reaches 8 weeks of age, and some may not be applied until the kitten is 12 weeks old.
Capstar is a type of flea-killing product that is administered orally to kittens as early as 4 weeks of age. It begins to kill fleas right away and works within 6 hours to kill off 90 percent of the fleas on the kitten. Most vets recommend Capstar because it kills quickly and is easy to administer.
Flea-control products are divided into two types: the type that kills live fleas right away and those that affect the eggs and larvae of the fleas. After adult fleas are killed off, killing the offspring, which includes the larvae and the flea eggs, prevents reinfestation of the kitten.
Products that kill larvae and eggs are known as insect growth regulators or IGRs. They are useful when treating the kitten and its environment to kill off any remaining offspring and keep the kitten from getting fleas again.
Popular topical treatments for killing fleas on kittens include Cheristin, Fiproguard Max, Pet Armor, Frontline Tritak and Advantage II.