About Capstar
Capstar is the brand name for nitenpyram, an oral flea tablet now owned by PetIQ, LLC (Nasdaq: PETQ), a pet health and wellness company headquartered in Eagle, Idaho. PetIQ acquired the Capstar portfolio from Elanco Animal Health in 2020 in a $95 million deal, at which point Capstar was already the top-selling oral over-the-counter flea treatment in the United States, and the brand still markets itself as America's #1 Oral Flea Treatment Brand in Retail.
The tablet's active ingredient begins killing adult fleas within about 30 minutes, a speed corroborated by independent veterinary coverage at Cats.com, which cites a 99% kill rate for adult fleas within three to six hours. Nitenpyram carries an unusually wide safety margin -- studied at ten times the labeled dose for 30 days without adverse effects -- which is why it is approved for kittens as young as four weeks and two pounds, the widest age and weight window of any oral flea product we reviewed.
Brand website: capstarpet.com
What Capstar makes
Capstar's range runs wider than the products we review. The lines we know best from our own testing are marked with a star:
CAPSTAR Oral Flea Treatment for Cats
Nitenpyram tablets in 6- and 12-dose packs for cats 2-25 lbs — featured on House of Mittens
CAPSTAR + NEXTSTAR Combo for Cats
Oral tablet bundled with a month of NextStar topical prevention — featured on House of Mittens
NEXTSTAR Topical Flea & Tick Treatment for Cats
Standalone monthly spot-on preventive sold separately from the oral tablet
CAPSTAR Oral Flea Treatment for Dogs
Same nitenpyram formula dosed for small dogs
CAPSTAR for Large Dogs
Higher-dose nitenpyram tablets for large-breed dogs
Why we recognized Capstar
The House of Mittens Top Brand recognition isn't paid for and can't be applied for. We award it to the brands whose products consistently stand out in our vet-reviewed category guides. Capstar earned it on the strength of the products below, evaluated the same way every product on this site is: assessed against feline-health criteria, used with real cats, and judged on merit.
Capstar products we rated highly
Capstar (nitenpyram) Cat Flea Treatment, Fast-Acting Oral Flea Treatment for Cats 2-25 lbs (6 Doses)
Starts killing adult fleas in about 30 minutes and clears the great majority of them within hours, faster than anything else available without a prescription. Approved for kittens from four weeks and two pounds, the widest age and size window in the category, and safe to redose as often as once a day during a heavy outbreak.
Read the Best Oral Flea Treatments for Cats of 2026 guide →
CAPSTAR Flea Treatment for Cats 2-25 lbs (6 Doses) + NEXTSTAR Flea and Tick Prevention for Cats Over 3.5 lbs (1 Dose) Bundle
Pairs the fast oral knockdown with a month of NextStar topical prevention in one purchase, solving the two-part problem a flea infestation actually requires -- immediate relief plus ongoing protection -- and works out cheaper than buying the tablets and a monthly preventive separately.
Read the Best Oral Flea Treatments for Cats of 2026 guide →
Capstar (nitenpyram) Cat Flea Treatment, Fast-Acting Oral Flea Treatment for Cats 2-25 lbs (12 Doses)
The twelve-dose box sized for multi-cat households, where every cat has to be dosed on the same day for treatment to work. A lower cost per tablet than the six-count box, with the same rapid, well-documented 30-minute action.
Read the Best Oral Flea Treatments for Cats of 2026 guide → Capstar (nitenpyram) Cat Flea Treatment, Fast-Acting Oral Flea Treatment (6 Doses)
The fastest flea kill in our full flea-treatment roundup, starting within about 30 minutes -- the pick for an active infestation that needs immediate relief before starting a longer-acting monthly preventive.
Read the 10 Best Flea Treatments for Cats of 2026 guide →What earned Capstar the recognition
- Fastest OTC flea knockdown in our testing: nitenpyram starts killing adult fleas within about 30 minutes, faster than any other over-the-counter option in our oral flea treatment roundup.
- Widest safety margin in the category -- safe for kittens from four weeks and two pounds, and studied at ten times the labeled dose for 30 days with no adverse effects.
- A top pick in our oral flea treatment reviews, and a standout in our broader flea treatment coverage for its fast-acting relief.
- The CAPSTAR + NEXTSTAR bundle pairs the fast oral knockdown with a month of topical prevention, addressing the full flea-control cycle in a single purchase, another of our top picks.
- America's top-selling oral OTC flea treatment brand in retail, according to the brand, and now part of PetIQ (Nasdaq: PETQ), a pet health and wellness company.