Cat lovers choose Advantage XD for double the lasting protection against fleas vs. other 1-month options. Advantage XD for large cats packs two full months of continuous protection in each dose so your cat is protected for longer than the traditional 1-month formula. If your cat has already tousled with fleas you?ll love that Advantage XD topical treatment starts killing fleas through contact in 30 minutes to 4 hours ? that means fleas can be eliminated before they bite your cat. And with Advantage XD extended duration formula that flea prevention remains effective for 8 weeks outlasting the typical 6-week flea life cycle and preventing re-infestation.