K9 ADVANTIX II Flea & Tick Spot Treatment for Dogs, 21-55 lbs, 6 Doses (6-mos. supply) - Chewy.com

K9 Advantix II Flea & Tick Spot Treatment for Dogs, 21-55 lbs

By K9 Advantix II
Rated 4.2696 out of 5 stars

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About This Item


  • Broad-spectrum, veterinarian-recommended treatment repels and kills fleas, ticks and mosquitoes on dogs 7 weeks or older and weighing 21-55 pounds.
  • Begins working within 12 hours and kills pests on contact.
  • Kills all life stages of fleas to prevent re-infestation; also kills lice and even repels biting flies.
  • Waterproof formula continues working for up to four weeks, even after bathing or swimming.
  • Convenient, monthly topical application contains imidacloprid, permethrin and pyriproxyfen; available in packs of 2, 4 or 6 treatments.

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Play Video: Learn More About K9 Advantix II From Our Team of Experts
Learn More About K9 Advantix II From Our Team of Experts

About K9 Advantix II

Experience the Advantages of K9 Advantix II

Veterinarian-recommended K9 Advantix II kills fleas, ticks, mosquitoes and lice, and repels biting flies. Now you can help your dog fight these pesky pests through contact—no biting required. Convenient and easy to use, K9 Advantix II is for dogs and puppies 7 weeks of age or older. So help your pal get the effective protection he needs with all of the advantages of K9 Advantix II.

Why are Biting Bugs a Big Deal?

K9 Advantix II spreads over the skin and hair to kill and repel them through contact, meaning they do not have to bite to die. And if a flea, tick or mosquito is repelled, it cannot bite and transmit disease.

Why Choose K9 Advantix II?

Fleas, ticks and mosquitoes can negatively affect your pet's health. It's important to use an effective product that kills pests which can spread disease. Fleas can cause flea allergy dermatitis, an allergic reaction that can lead to constant scratching, severe itching and even hair loss. Ticks can transmit deadly diseases, such as Lyme disease and Rocky Mountain spotted fever. And mosquitoes can potentially carry dangerous diseases, too, including heartworm. K9 Advantix II should not be used in place of a heartworm disease prevention product.

Is K9 Advantix II the Right Choice for Your Dog?

Whether your dog is a winter snow hound or a summer backyard explorer, an sunseeker or an outdoor enthusiast, choose K9 Advantix II to help keep fleas, ticks and mosquitoes from interrupting his favorite activities year-round. If you want to return the love to your dog, take care of him with flea prevention that works to kill the fleas you see and the ones you don't.

K9 Advantix II Has a Treatment for Dogs Large and Small


4-10 pounds


11-20 pounds


21-55 pounds


55 pounds and over

Do not use K9 Advantix II on cats.

About K9 Advantix II

K9 Advantix II is manufactured by Bayer, a leading name in the healthcare industry for over 150 years. K9 Advantix II is a monthly flea, tick and mosquito treatment for your dog that kills through contact—no biting required. It starts working to kill fleas within 12 hours of application and is veterinarian recommended, so you can feel confident knowing that your pet is getting effective protection.
Shop Bayer

Questions & Answers

31 Customer Questions

Do fleas have to bite my dog in order for the medication to work?
Answer by ChewySep 01, 2017
The Flea and Tick treatment works to kill even without the bugs biting.

Can I use K9 Advantix II on my indoor dogs if I have indoor cats?
Answer by ChewyOct 20, 2022
This flea and tick treatment should not be ingested. Cats should not come into contact with this product, so they should be placed in a different environment while this treatment is being applied.

How do you apply the topical treatment? Is it messy?
Answer by ChewySep 11, 2017
To apply, remove applicator tube from the package. Use scissors and peel down foil. Hold applicator tube in an upright position and pull the cap off the tube. Turn the cap around and place other end of cap back on tube. Twist cap to break seal, then remove cap from tube. The dog should be standing for easy application. The entire contents of the K9 Advantix II tube should be applied evenly on the top of the back from the shoulder to the base of the tail. At each spot, part the hair until the skin is visible. Place the tip of the tube on the skin and gently squeeze to expel a portion of the solution on the skin. Do not apply an excessive amount of solution at any one spot that could cause some of the solution to run off the side of the dog. Discard the empty tube.

I have an inside dog & was wondering if I treated my dog while he stayed inside if the fleas would jump off him & make their home in my house??
Answer by ChewyNov 21, 2017
This treatment kills pests on contact so, they won't invade your home.

ReviewsWrite a Review

Rated 4.2696 out of 5 stars
1291 Reviews
Would recommend to a friend

1291 Customer Reviews

Rated 1 out of 5 stars
By Emily on Jan 31, 2023

Bad Reaction!

My dog had a bad reaction to this treatment! It was my first time trying K9 Advantix on him (switching from a different topical treatment), and within a few hours he was clearly in pain, trying to scratch where it was applied and hiding under furniture. I parted his fur to look at the skin, and it was bright red and almost looked like it had been burned. I called the vet, and he urged me to give my dog a bath with Dawn dish soap to get all the stuff off him, and that seemed to help him calm down. It seems my dog has some kind of allergic reaction, and I definitely won’t be using this product again.

Rated 1 out of 5 stars
By Tori on Jan 1, 2023

Mini Berniedoodle had bad reaction

My dog Kevin who is a mini berniedoddle had a horrible reaction to this tick med. He was visibly very itchy and was rubbing his back in the snow. I looked closer and the places I put the medication his skin was very red. I washed it off him as much as I could immediately. It also smelt horrible.

Rated 5 out of 5 stars
By Lildog on Feb 6, 2023

Works great

Highly recommended, does not bother my dog when applied and works longer than a month and works well. Does not have a strong odor either

Rated 1 out of 5 stars
By pbnjz on Oct 11, 2022

K9advantix II

Awful.. Spent over $100 trusted in the name and my dog has been suffering for 2 months. I was so sure it was not the drops I even argued with my veterinarian claiming the drops were working but to my ignorance they were not!! Now I've had to buy antibiotics and ointments to try to relieve his skin condition and now that I've put him on NexGard it's all cleared up. Very disappointed. I'm a grandma who now inherited and raising a granddaughter and her pup on a limited budget.

Rated 5 out of 5 stars
By TSquared13 on Feb 4, 2023


Best flea, tick AND mosquito defense available on the market. The application is easy to apply and works!

Rated 2 out of 5 stars
By molly on Nov 3, 2022

k9 advantix

i used it since the from the 20th of september ,molly still has very bad itching problem. this is why no one wanted her . i live on 800 a MONTH HAVE A FRACTURED SPINE AND ALMOST GIVING UP I DONT HAVE A EXTRA DIME FOR THIS CONSTANT ISSUE. THE FLEA JUICE SOME WHAT HELPED AFTER 15 DAYS FLEAS WERE BACK

Rated 4 out of 5 stars
By Isabelle on Dec 9, 2022

Worked at first

This seemed to work the first couple days, then it lost the effectiveness. I found live flea on my dog within a week and a half of the application.

Rated 1 out of 5 stars
By EhMf on Dec 7, 2022

Did not work

Bought two 6 month boxes and did not help my dogs at all. It says kills fleas within 12 hours but they were still crawling around all over them.

Rated 1 out of 5 stars
By ACEG on Nov 6, 2022

Still have live ticks

I’ve had it on my dog a week. I am still finding large, blood filled ticks on my dog. I understand they have to bite her to work but they should die before they get engorged. Not happy with product.

Rated 1 out of 5 stars
By Mashuga on Nov 12, 2022

Waste of money

Noticed within hours my dogs didn’t feel good. That lasted over 24 hours. Never saw a reduction in fleas. Huge waste of money! I will never purchase this brand again.