About This Fast-Acting Flea Treatment: Capstar (nitenpyram) starts eliminating adult fleas in just 30 minutes Tackle Flea Infestations Fast: With one dose of CAPSTAR, you can watch the dead fleas fall off your pet Treat Reinfestations Fast: If your pet gets reinfested with fleas, simply give another dose as often as once a day No Prescription Needed: Fast, effective flea treatment that's available over the counter Intended Use: Capstar Oral Flea Treatment for Large Dogs (57 mg) is safe for dogs and puppies 4 weeks and older that weigh 25.1-125 pounds