Oral tablet kills fleas and is for the treatment of flea infestations on dogs and puppies 4 weeks of age or older and 2 lbs body weight or greater. Begins working within 30 minutes 90% effective against adult fleas on dogs within 4 hours. Kills fleas that may cause flea allergy dermatitis. 2-25 lb tablet contains 11.4 mg nitenpryam. 25+ lb tablet contains 57 mg nitenpyram.