How FRONTLINE® Brand Products Work - From the very first application, FRONTLINE products kill up to 100% of existing fleas in less than 24 hours and continues to provide fast-acting, long-lasting flea and tick control.

Fipronil, the active ingredient in all FRONTLINE Brand Products, is stored under your pet's skin, in the oil glands, so FRONTLINE continuously reapplies to the skin and hair through the hair follicles making it waterproof.

FRONTLINE will remain waterproof and won’t rinse off – even through your cat’s self-grooming or your dog’s monthly bath or swim. In fact, FRONTLINE doesn't stop working for an entire month, giving your pet non-stop flea and tick control.



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