Advantage is a specialist spot-on that protects your pet, without a prescription. Our homes wouldn't be the same without our pets, but they sometimes bring parasites through the door. Fleas are particularly unpleasant because they don't just harm your cat or dog – they're also a risk to everyone else in the home. Advantage kills fleas on your pet within 24 hours, as well as flea larvae in the home wherever the treated pet goes.