Contains Fipronil the active ingredient used in Frontline® - Top Spot for Cats* Fast-Acting, Long-Lasting Kills Fleas Kills Ticks Kills Chewing Lice Waterproof Kills Fleas, Ticks & Lice Flea+Tick Defense for Cats contains the active ingredient fipronil that effectively targets fleas, ticks, and chewing lice. Fipronil collects in the oils of the skin and hair follicles, and continues to be released from hair follicles onto the skin and coat, resulting in long-lasting activity. Fleas Kills adult fleas before they lay eggs Controls and prevents re-infestation Kills fleas that may cause anemia Protects for one month Controls fleas which may cause flea allergy dermatitis Ticks Kills ticks that may transmit Lyme disease, ehrlichiosis, and babesiosis Lice Rapidly eliminates infestations with chewing lice