K9 Advantix II Medium Dog Flea, Tick & Mosquito Treatment — 11–20 lb, 4‑Month Waterproof Spot‑On

K9 Advantix II Medium Dog is a monthly topical treatment that kills and repels fleas, ticks, mosquitoes, biting flies and lice for dogs weighing 11–20 lbs.

If you want a vet-recommended, easy-to-apply spot-on that acts quickly and keeps working through outdoor play and bath time, this 4-dose pack delivers four months of protection. The formula begins killing fleas within 12 hours of application and repels pests so they are less likely to bite, helping break the flea lifecycle and reduce new infestations. It’s fragrance-free, becomes waterproof after 24 hours, and is designed for dogs at least 7 weeks old.

How fast does this treatment stop fleas and prevent reinfestation?

The active ingredients act rapidly to kill adult fleas on contact, typically within 12 hours of the first application. By eliminating adult fleas before they can lay eggs, the product reduces future generations and helps stop an existing infestation from expanding.

• Kills adult fleas within 12 hours
• Acts on contact so fleas don’t need to bite to die
• Monthly reapplication maintains continuous protection
• Helps interrupt the flea life cycle to limit egg production

Will this protect my dog from ticks, mosquitoes and other biting pests?

Yes—K9 Advantix II is formulated to both kill and repel several external parasites, including multiple tick species and mosquitoes. The repellent action reduces the chance of pest attachment and biting, while the insecticidal action removes adults present on the dog.

• Repels and kills mosquitoes to reduce biting pressure
• Effective against common ticks that attach to dogs
• Also controls biting flies and lice encountered outdoors
• Suitable for dogs that spend time both inside and outside

How is the product applied and does it withstand baths or rain?

Application is a simple spot-on: part the fur at the base of the neck and apply the liquid directly to the skin in the indicated locations. The formula becomes waterproof after 24 hours, so normal outdoor activity and brief exposure to water won’t immediately reduce protection.

• Quick topical application—goes on in seconds
• Fragrance-free, non-greasy finish
• Waterproof after 24 hours to maintain efficacy during outdoor play
• No pills or collars required—ideal for dogs that resist oral or collar options

Are there age, weight or safety limits I should know?

Use only on dogs 7 weeks of age or older and weigh between 11 and 20 pounds for the Medium formulation. Always read and follow label instructions for dosing and safety, and consult your veterinarian if your pet has health issues or is taking medications.

• For dogs 11–20 lbs only—select correct size for other weights
• Approved for dogs at least 7 weeks old
• Over-the-counter availability—no prescription required
• Check the product leaflet for potential side effects and precautions

Who is this for: K9 Advantix II Medium Dog is aimed at owners of small-to-medium dogs (11–20 lbs) who want a fast-acting, monthly topical solution to control fleas, ticks, mosquitoes, biting flies and lice. It’s a practical choice for pets that spend time outdoors or live in flea-and-tick-prone areas and for families preferring a scent-free, waterproof option that’s easy to apply without a prescription. Choose the 4-dose pack to cover four monthly treatments and keep your dog protected through the season.

Ingredients

Imidacloprid, Permethrin, Pyriproxyfen