Novartis Capstar Flea Treatment - Blue - 2-25 lb - 6 count Very fast acting flea treatment that starts killing within 30minutes. Short-term treatment for 4 weeks and older puppies and dogs. Starts acting within 30 minutes of administration and kills 100% fleas within 7 hours. A non-topical treatment is easy to administer and does not leave residue or cause discoloration of the pet's skin. It is safe to treat pregnant and nursing dogs.