Zodiac Double Action Flea & Tick Shampoo for Dogs and Cats is enriched with oatmeal, coconut oil, lanolin and aloe to condition and soothe sensitive skin while killing adult cat fleas, dog fleas and American dog and Brown dog ticks. The shampoo leaves your pet's coat soft, shiny and manageable as it continues to kill flea eggs for up to 4 weeks. Application once a month should be adequate given the residual control. For severe flea problems, treatments can be performed weekly.