Effipro spot-on Cat based on fipronil is a flea and tick remedy for cats. A specially designed dropper for Effipro, the Drop-Stop dropper, is quick and can be opened in a single motion. Liquid will only come out of the dropper if the reservoir is pressurised, so that it stops immediately when the cat moves away. This will ensure the full dose to reach the cat at the right time. Effipro spot-on kills the present fleas and ticks on the animal. Ticks usually fall off within 24-48 hours for two weeks. Repeat when necessary.