From the Manufacturer:
Hartz First Defense Topical Treatment for Cats 3 lbs or more kills Fleas, Ticks, and Chewing Lice as well as prevents and controls re-infestations. Fast acting, long lasting, waterproof formulation remains effective even after bathing, water immersion, or exposure to light.
** These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure or prevent any disease.
For use only on Cats & Kittens 8 weeks and older weighing 3lbs or more
Kills fleas, ticks, chewing lice
Prevents and controls reinfestations
Fast acting, Long lasting, and Waterproof