For dogs and puppies 8 weeks or older weighing up to 22 lbs. No prescription required! Use this supply of flea and tick medication to keep your pet comfortable and pest-free. This powerful formula kills fleas, ticks and chewing lice within 48 hours of application and continues working to protect your pet for up to 4 weeks. The formula is waterproof to keep it from washing off. Product Features: -For dogs 8 weeks or older -Apply once a month to control fleas, ticks and chewing lice -Formula is waterproof for staying power \- Helps keep your pet safe from Lyme disease EPA approved product guaranteed from the manufacturer, Merial