Best Flea & Tick Prevention

Seresto is the set-and-forget option for owners who won't keep up with monthly treatments: one collar covers up to eight months, which on this 2-pack works out to about $6.25 per collar-month. EPA completed its review in July 2023 and kept the registration for five years, with new label warnings and added incident-reporting requirements for Elanco; in February 2024 EPA's Inspector General said the agency still needed to determine whether the collars pose an unreasonable risk to pets. Buy from Amazon or Elanco directly, since counterfeits circulate on secondary marketplaces, and remove the collar if you see a skin reaction.

Frontline Plus is the reliable workhorse of flea and tick prevention — it's been the vet-office staple for over 20 years for good reason. The topical formula kills all flea life stages and stays effective through baths and swimming. If your dog tolerates the monthly application, this remains one of the most battle-tested options available.

K9 Advantix II is the over-the-counter topical for owners who want ticks and mosquitoes repelled as well as killed. Elanco's EPA-registered label covers fleas, ticks, mosquitoes, biting flies and lice for 30 days per dose. The permethrin in it is toxic to cats: the label says do not use on cats, so it is the wrong choice for a dog that shares a bed or grooms with a cat.

Advantage II is the flea-only topical in Elanco's range: an EPA-registered imidacloprid and pyriproxyfen spot-on that kills adult fleas and stops eggs and larvae developing. It does not kill ticks, so it suits dogs in low-tick areas or owners who handle ticks another way. The six-dose pack covers half a year.