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

By K9 Advantix II
Rated 4.3955 out of 5 stars
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K9 Advantix II Flea & Tick Spot Treatment for Dogs, 21-55 lbs, 6 Doses (6-mos. supply) slide 1 of 9
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K9 Advantix II Flea & Tick Spot Treatment for Dogs, 21-55 lbs, 6 Doses (6-mos. supply) slide 1 of 9

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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.
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

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Top IngredientsActive Ingredients: Imidacloprid 8.80%, Permethrin 44.00%, Pyriproxyfen 0.44%...Active Ingredients: Imidacloprid 8.80%, Permethrin 44.00%, Pyriproxyfen 0.44%....Fipronil: 6.0%, Permethrin: 44.8%, Pyriproxyfen: 1.8%...Fipronil: 6.0%, Permethrin: 44.8%, Pyriproxyfen: 1.8%...Active Ingredients: Imidacloprid 8.80%, Permethrin 44.00%, Pyriproxyfen 0.44%....
Breed SizeSmall Breeds, Medium BreedsLarge Breeds, Giant BreedsMedium Breeds, Large BreedsLarge Breeds, Giant BreedsSmall Breeds

Questions & Answers

36 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.

If my dog is 26lbs would I use the entire single use tube or about half? 21-55lbs seems like a large range when it comes to topical pesticides.
Answer by ChewyMar 09, 2018
This Treatment is formulated for dogs weighing anywhere between 21-55 pounds. It is recommended to use a complete tube per pet.

Can I use K9 Advantix II on my indoor dogs if I have indoor cats?
Answer by ChewyJul 02, 2017
Cats should not come into contact with this product, so they should be placed in a different environment while this item 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.

ReviewsWrite a Review

Rated 4.3955 out of 5 stars
1201 Reviews
Would recommend to a friend

1201 Customer Reviews

Rated 5 out of 5 stars
By WelshieMom on Apr 27, 2022

It works! It works!

After using Frontline Plus (fipronil) forever and *never* seeing a flea on any of my pets, I was shocked to see a couple fleas on my dog last month. I did a ridiculous amount of research and, with my vet’s approval, switched to K9 Advantix II. I applied it last night and as of this morning there are NO live fleas on my dog! (I found two, both dead.) I hope this will be the end of our new, sudden flea problem. I also really like that the Advantix vials are smaller, easier to open, and far less messy and stinky than the Frontline. Very happy with this product.

Rated 1 out of 5 stars
By Disappointed on Apr 30, 2022

not working

I used this on two Jack Russell terriers and have pulled live engorged ticks off of both of them. I also used the larger size on my Border Collie and pulled a large, live engorged tick off of her. The treatment had been done more than a week before finding the ticks. Very disappointing.

Rated 5 out of 5 stars
By Pmedic on May 6, 2022

No more worries for our babies

We’re firm believers in k-9 advantix, we use it for for both our big babies! Since we’ve started using it, we’ve not had a problem at all with fleas or ticks! We train our dogs in our woods, which is lots of a of fleas and ticks

Rated 5 out of 5 stars
By Belle on May 4, 2022

Tick Protection

We used another brand previously with inferior results. Our Brittany is an active bird dog during the pheasant season and loves to lay in the grass outside when the weather allows. Advantix minimizes tick issues very effectively.

Rated 5 out of 5 stars
By Shelly on Mar 8, 2022


It was wonderful that I was able to purchase K9 Advantix II for my dog in just a 2 dose package. Unfortunately, my 13 year old English Springer Spaniel is on his last journey and not sure how much longer he has. I wanted to continue with his flea and tick meds but did not want to purchase another 6 month supply as I did in the past. This package containing 2 doses was perfect!

Rated 5 out of 5 stars
By Chelle on May 14, 2022

works great

Have been using this for years. Both dogs have allergies, and tried other brands before deciding on this one. I’d recommend it

Rated 4 out of 5 stars
By Dana on Feb 26, 2022

Good so far

Before I purchased this medicine I talked to my vet. I asked his advice on the kind of insects I should get protection from. My vet said the usual fleas, tics, etc., but he mentioned flies and mosquitoes, those are things I hadn't thought about. This medicine covers those and so far it's been doing a stellar job. I do have to give some advice though....#1. Put it on first thing in the morning because it takes a while to absorb and cover your dog. #2 Don't be too alarmed if your pet acts kind of sick, like laying around, looking blah. This is strong stuff, follow directions and read all warnings, and give plenty of water. It works.

Rated 5 out of 5 stars
By TJQ1 on Mar 26, 2022

Great product. Easy to use & very effective.

Chewy is a very good company to do business with. Prices are competitive, service is quick & even though I personally have never had a problem, I’m sure they would go out of their way to resolve any issues.

Rated 5 out of 5 stars
By Zorro on Apr 21, 2022

Keeps me and my pups safe!

Easy to apply and it's great keeping us all safe! I use these every month without fail especially since I live in the woods. Great to have!

Rated 5 out of 5 stars
By Shar on Apr 24, 2022

Stock up for a great price

Best price so I stocked up. I love chewy I recommend to everyone.I would love to work at this company