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

By K9 Advantix II
Rated 4.2036 out of 5 stars

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$75.98Chewy Price
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Total Price: $152.44

About This Item


  • Helps to protect dogs weighing 21 to 55 pounds from fleas, ticks, mosquitoes, biting flies and lice.
  • Starts working within hours of application.
  • Kills and repels on contact, so fleas don’t have to bite your furbaby to die.
  • Easy-to-apply topical treatment is fragrance-free and waterproof after 24 hours.
  • No prescription needed.

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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.
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Questions & Answers

31 Customer Questions

Do fleas have to bite my dog in order for the medication to work?
Answer by ChewyFeb 16, 2023
This preventive kills through contact and no biting is necessary for it to be effective.

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 4.2036 out of 5 stars
1370 Ratings
Would recommend to a friend

1369 Customer Reviews

Always consult a veterinarian about your pet’s health needs. Customer reviews should not be used as medical advice.
Rated 1 out of 5 stars
By SP on Sep 27, 2023

Gave my dog chemical burns

We were using this during the summer as I didn’t want to add another pill to her monthly medication. A couple months into usage, my dog would start shaking every time we would pull this out. Eventually we figured out that it was causing her burns since we took a better look under her fur. Do not use!!

Rated 5 out of 5 stars
By PupNamedCosmo on Aug 4, 2023

This one protects against everything I need it to. Works great! I used on our long haired,60lb puppy. Hes an indoor dog, but hikes on the river trails daily. We dont have any flea issues. Its good stuff. As a matter of fact, not only do I reccommend to friends, I shared my 6month supply, so a freind's dogs could find releif immediately, rather than have to wait to receive it by mail, since their dogs, since they were beign attacked by bitting flies. Its a life saver!

Rated 1 out of 5 stars
By Cj on Aug 24, 2023

User beware

Within a few hours of putting this on our Basset Hound for the 1st time she had a seizure. She has no prior issue with seizures before using this product. This product may do well with killing pests off your dog's but at what cost to their health. Highly do NOT recommend!! (Purchased from a local store, not chewy)

Rated 1 out of 5 stars
By Ollie on Jul 24, 2023

Careful they didn’t work

Didn’t work! I have never found ticks in my dog before other than once and luckily found it right away however I knew this season was bad and tried this instead of the collar , however he was infested and I know it claims to kill them off but I picked them all off and must of missed one and it never died didn’t find it until it was almost the size of a quarter because it’s location scary stuff considering my son got Lyme disease that same week

Rated 4 out of 5 stars
By Michelle on Aug 3, 2023

K9 Advantix II

I was looking for a product that would cover all the sizes of my 5 dog pack. This product was prefect for their weights. We have only used it for a few weeks and I gave them all baths a couple days before using it. But as far as I can see it has helped with the fleas and itching. Much better than Frontline Plus and the price on K9 Advantix was better.

Rated 4 out of 5 stars
By Christine on Aug 13, 2023

Does not repel mosquitoes

I have no complaints about this product, except that it does nothing in regards to mosquitoes. We have a lot this year, and they pester my dog all the time. The manufacturer should not be making this claim. (I have now treated my yard now with Wondercide which has helped).

Rated 1 out of 5 stars
By HideyHo on Jun 25, 2023

Does not repel or kill ticks

Super disappointed! We have a cabin in northern Wisconsin we spend a lot of time at. Our yard is manicured but we do walk and my pooch romps through the woods. Tick prevention is critical! Unfortunately, this product does not repel or kill ticks. We "tick check" several times a day and always after our walks. We almost ALWAYS find a tick crawling on his legs and sometimes we miss them and they are attached. They are not dead. It also does not repel biting flies. I don't know if it repels fleas as we have not had this issue. I am very diligent in applying as prescribed. Will not buy this product again and would not recommend it. Am giving one star only because I have to select something.

Rated 5 out of 5 stars