Nitenpyram
Capstar is a brand-name oral flea medication for dogs and cats that provides rapid relief from flea infestations. The active ingredient, nitenpyram, is an insecticide that starts killing fleas within 30 minutes of administration. This medication is primarily used for treating existing flea problems and can be given to puppies and kittens as young as 4 weeks old.
Capstar is a fast-acting oral flea treatment for dogs and cats that kills adult fleas within hours of administration.
Key facts at a glance
- RxNorm
- 880635
- Generic
- Capstar
- Class
- brand-name
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- —
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Capstar is indicated for the treatment of flea infestations in dogs and cats. It is effective against adult fleas and provides relief from itching and discomfort caused by flea bites. It can be used in pets of various ages, including puppies and kittens at least 4 weeks old and weighing at least 2 pounds.
Capstar contains nitenpyram, an insecticide that belongs to the neonicotinoid class of drugs. It works by interfering with the nervous system of fleas, causing paralysis and death. The medication is absorbed into the bloodstream after oral administration, and fleas are killed when they bite the treated pet.
Capstar is for oral use only and should be given according to the pet's weight. While side effects are rare, some pets may experience increased scratching (which indicates the medication is working), hyperactivity, or lethargy. It may be used in combination with other flea control products and should be administered daily or as needed until fleas are under control. Consult a veterinarian before use, especially for pets with known health conditions.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 26, 2026. · Read our editorial policy