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

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

By K9 Advantix II
Rated 4.2034 out of 5 stars

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About This Item


  • Helps to protect dogs over 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

Important Information

Fleas rise to the top of your pet's coat as they die, so consider it a triumph if you start seeing more fleas at first, after treating your pet. If you’re still seeing fleas after application, it may be because your pet has picked up new fleas from the environment, which may include other pets, surfaces and outdoor areas. It may take up to 30 days to break the entire flea life cycle. Additionally, you should also treat sources of new fleas (i.e., carpet, yard, etc.) to ensure complete flea control.

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

Where is the manufacturer date on the box?
Answer by PigpandiMay 09, 2023
On back in bottom left cornergood for 18 months from that date

Will Advanix kill Heartworms as will as Flea's and Ticks
Answer by ChewyJun 02, 2021
This treatment is specifically formulated to repel and kill fleas, ticks and mosquitoes. It kills all life stages of fleas to prevent re-infestation and also kills lice and repels biting flies.

Can this product be used on pregnant dogs?
Answer by ChewyMay 21, 2018
K9 Advantix II is suitable for use with a pregnant or lactating dog.

Can I use both this along with the collar flea preventer?
Answer by ChewyAug 15, 2018
We encourage speaking with your Veterinarian before combining supplements, for the safest opinion.

ReviewsWrite a Review

Rated 4.2034 out of 5 stars
1731 Ratings
Would recommend to a friend

1731 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 Esther on May 22, 2023

ticks after ticks

I have been using it for last 2 months and during the 2 months of time i have seen more ticks around my dog than i have ever in my entire life. My dog was on frontline for 4 years with no problem until he had fleas last year which then i had to switch to Nexgard. But Nexgard being too strong and expensive, i thought i would try K9 Advantix ii this year. From the beginning, it didn’t repel him from getting a mosquito bite and then…i would find a tick here and there weekly. And today, i grabbed a grain thing around my dog after he finished his lunch and omg….omg… it was a fully fed fat tick. I freaked out because i have never found one that well fed on my dog before. We are going back to nexgard.

Rated 1 out of 5 stars
By Diane on Jun 3, 2023

K9 Advantix II

I decided to use this tropical on one of my dogs. Bad idea. He was itching and biting himself something terrible. I checked his skin but no rash, just itchy. He is rolling around biting hisself. My husband and I took him out in the backyard and shampooed his back. He seems to have calmed down a little. Will take him to the vet tomorrow if this still persists. DO NOT BUY THIS PRODUCT!!!!

Rated 2 out of 5 stars
By Sucks on Jun 3, 2023

Waste of money

I've used this for two months now and my dog has fleas. She is scratching all the time and even creating wounds. I feel horrible, and I don't know what to do besides brush and bathe her every day because I can't apply a different flea treatment for another three weeks. It's very disappointing and a waste of money!

Rated 2 out of 5 stars
By HugosMom on May 17, 2023

Found ticks two weeks after applying.

I haven’t had a problem with fleas or mosquitos on my dog, but the ticks are the main reason I bought this topical, and it doesn’t seem to help with keeping them off at all. I will use my second dose at the 4 week mark and will see if anything changes. Going to try a different brand next round and hopefully will have better results!

Rated 1 out of 5 stars
By KF on May 18, 2023

Doesn’t Work

We found fleas on our Golden Retriever and immediately ordered this. We bathed her and once dry we gave her this topical treatment. It’s been 1 week - and we are still finding fleas on her!! Doesn’t work. Save your money. They say the chewables work much better, that’s what we’re trying next - from a different brand!

Rated 2 out of 5 stars
By BB on May 18, 2023

Totally upset after using this product for 8 years

I have been using K9 Advantix II on my 8 year old Lab ever since she was old enough for flea/tick meds and it always worked great until yesterday when I found a tick on her that was attached and then today there were 2 more. We do a lot of hiking and never had any issues until yesterday. Ugh so totally upset.

Rated 3 out of 5 stars
By Jli on Jun 2, 2023


Initially she responded well to the product and the fleas died off. Unfortunately, in less than a month, she's scratching again. My yard and house have been treated. I don't want to give her an oral medication but may have to.

Rated 1 out of 5 stars
By Benjamin on Apr 19, 2023

Does Not Work

I've been buying this in bulk for awhile now and haven't had problems in the past. This year is another story. Despite the claim on the front of the box, this product DOES NOT repel or kill fleas. I've got 5 unopened boxes, so I called Elanco (the company listed on the box) and they tried to argue semantics about the word "repel" and how it doesn't actually mean that it will keep fleas away from dogs or prevent them from laying eggs or biting. They denied my reimbursement and hung up on me when I asked for clarification. So now I've got 5 boxes of this useless product, a house full of fleas, and 3 large, uncomfortable dogs unable to sleep through the night without itching. So thanks, K9 Advantix II for being a complete waste of money but more importantly for making my house an incredibly stressful place to be. I've already started an auto-ship with Bravecto, and I encourage anyone else to not buy K9 Advantix II unless you prefer having to wash every fabric item in your home.

Rated 1 out of 5 stars
By farmgirl on May 17, 2023

If I could give it 0 stars I would!!

I put this on both of my big dogs and 3wks later I have picked off 30+ ticks off of each dog (that is 60+ ticks total) and they are all alive!!!! This stuff is horrible! My vet said they definitely don’t recommend it and I sure do not either!

Rated 5 out of 5 stars
By TitansDad on May 11, 2023

Chewy rocks

Great prices, fast shipping and excellent service. I have several collars from them, and when I was slightly displeased with the width of one of them, the response from Chewy was immediate and above and beyond. I will absolutely stay loyal to Chewy.