About Frontline
FRONTLINE was introduced in 1996 and built its reputation as a flagship product of Merial, the animal-health joint venture formed by Merck and Sanofi-Aventis. When Boehringer Ingelheim acquired Merial in January 2017, FRONTLINE was folded into Boehringer Ingelheim's animal health portfolio, where it's now manufactured and marketed by Boehringer Ingelheim Animal Health USA Inc. That three-decade run under a handful of owners is unusual in a category where private-label and store-brand fipronil products come and go -- FRONTLINE says it has sold more than 1 billion doses since launch.
The core FRONTLINE Plus formula pairs fipronil with the insect growth regulator (S)-methoprene to kill adult fleas, flea eggs, flea larvae, ticks, and chewing lice in a single monthly topical application, and the line has since expanded to FRONTLINE Gold, which adds a third active (pyriproxyfen) for additional egg and larva control. Both are EPA-registered and waterproof once dry. Beyond the product line, the company has also publicized donating more than 1,000,000 doses of FRONTLINE to animal shelters, Native American reservations, and disaster-relief efforts.
Brand website: frontline.com
What Frontline makes
Frontline's range runs wider than the products we review. The lines we know best from our own testing are marked with a star:
FRONTLINE Plus for Cats & Kittens
monthly topical spot-on -- fipronil plus (S)-methoprene against fleas, ticks, and chewing lice -- the line our two featured picks belong to — featured on House of Mittens
FRONTLINE Gold for Cats
triple-action formula that adds pyriproxyfen for extra flea egg and larva control
FRONTLINE Plus for Dogs
the dog-formulated version of the same fipronil plus (S)-methoprene topical
FRONTLINE Gold for Dogs
triple-action dog topical, same third active as the cat Gold formula
FRONTLINE Shield for Dogs
adds mosquito protection on top of flea, tick, and lice coverage; dog-only
Why we recognized Frontline
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. Frontline 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.
Frontline products we rated highly
FRONTLINE Plus Flea & Tick Spot Treatment for Cat & Kitten (Green) Count of 6
Kills fleas, flea eggs and larvae, chewing lice, and ticks in one monthly topical -- broader coverage than the flea-only spot-ons it competes with, which matters for any cat with outdoor exposure. It's waterproof 24 hours after application, so a self-grooming cat or an accidental splash doesn't undo the dose, and it carries a deeper base of owner reviews than any other product across both of our flea-treatment roundups.
Read the 10 Best Flea Treatments for Cats of 2026 guide →
FRONTLINE Plus Flea & Tick Spot Treatment for Cat & Kitten (Count of 3)
The monthly pairing partner we recommend alongside a fast-acting oral tablet: it covers ticks and chewing lice on top of fleas, includes an insect growth regulator that kills eggs and larvae in the household rather than just fleas on the cat, and stays waterproof once dry so a mid-month bath doesn't strip the protection.
Read the Best Oral Flea Treatments for Cats of 2026 guide →What earned Frontline the recognition
- One of the products we rated highest in our flea treatment reviews, and the most trusted broad-spectrum monthly topical we evaluated.
- Also a standout in our oral flea treatment coverage, as the monthly tick-and-egg-control partner we pair with a fast-acting oral tablet.
- Broad-spectrum protection against fleas, flea eggs, larvae, chewing lice, and ticks from a single monthly application of fipronil plus (S)-methoprene.
- A three-decade track record since its 1996 introduction, carried from Merial through Boehringer Ingelheim's 2017 acquisition, with more than 1 billion doses sold and a deeper base of owner reviews than nearly any other product we evaluated.
- Waterproof within 24 hours of application, so routine grooming or an accidental splash doesn't undo the monthly dose.