Effipro contains fipronil as its active ingredient. Fipronil is the most widely used flea and tick control agent worldwide. Effipro is available as Effipro spot-on for dog, Effipro spot-on for cat and a spray suitable for dog and cat. The spray works against fleas and ticks as well as lice in dogs and cats. Virbac Effipro Spray is effective against fleas in cats for up to 6 weeks and against ticks for up to 4 weeks. If you use the spray for the dog, it is protected against fleas for up to 3 months and against ticks for up to 4 weeks, depending on the environmental pressure.