Itch Flea is applied topically to your pet's skin to prevent and treat external parasites including fleas, ticks and biting lice. Itch contains two active ingredients: Fipronil and (S)-methoprene.
Fipronil kills live adult fleas, lice and ticks on contact by interfering with the parasites' central nervous systems. This leads to paralysis and death - Sorry fleas!
(S)-methoprene is a growth inhibitor which works by penetrating the shell of newly laid eggs or by being absorbed through the immature fleas' body surface to prevent their growth and further development into adults, thereby limiting an ongoing infestation.
Following application of the product these ingredients are stored in the hair follicles and oil glands of your pet's coat and distributed over the skin and coat for a month, killing fleas and ticks as they come into contact with your pet's skin. You can find more information on this here.