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

By K9 Advantix II
Rated 4.3847 out of 5 stars
Slide 1 of 7
K9 Advantix II Flea & Tick Spot Treatment for Dogs, 21-55 lbs, 1 Dose (1-mo. supply) slide 1 of 7
Slide 1 of 7
K9 Advantix II Flea & Tick Spot Treatment for Dogs, 21-55 lbs, 1 Dose (1-mo. supply) slide 1 of 7

$16.98Chewy Price
$16.13Autoship Price
Autoship (Save an extra 5%)
Choose Autoship at checkout for regular deliveries.

Why Autoship?

  • FREE access to chat with licensed vets 7 days a week.
  • Save 5% on all future Autoship orders.
  • No fees, no commitments - cancel Autoship anytime.

In Stock
FREE 1-3 day shipping over $49

Frequently Bought Together

This Item - K9 Advantix II Flea & Tick Spot Treatment for Dogs, 21-55 lbs, 1 Dose (1-mo. supply)
Rated 4.3847 out of 5 stars
$16.98Chewy Price
Heartgard Plus Chew for Dogs, 26-50 lbs, (Green Box), 1 Chew (1-mo. supply)
Rated 4.9357 out of 5 stars
$11.99Chewy Price
Interceptor Plus Chew for Dogs, 25.1-50 lbs, (Yellow Box), 1 Chew (1-mo. supply)
Rated 4.7026 out of 5 stars
$10.39Chewy Price
Total Price: $0.00

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

Compare Similar Items

Customer Rating
Rated 4.3847 out of 5 stars
Rated 4.3166 out of 5 stars
Rated 3.3333 out of 5 stars
Rated 2.7143 out of 5 stars
Rated 2.5556 out of 5 stars
$16.98Chewy Price
$16.98Chewy Price
$14.99Chewy Price
$13.99Chewy Price
$18.74Chewy Price
$16.13Chewy Price
$16.13Chewy Price
$14.24Chewy Price
$13.29Chewy Price
$17.80Chewy Price
Top IngredientsActive Ingredients: Imidacloprid 8.80%, Permethrin 44.00%, Pyriproxyfen 0.44%...Active Ingredients: Imidacloprid 8.80%, Permethrin 44.00%, Pyriproxyfen 0.44%....Permethrin: 45%, S-Methoprene: 3%, Other Ingredients: 52%.Permethrin: 45%, S-Methoprene: 3%, Other Ingredients: 52%.Permethrin: 45%, S-Methoprene: 3%, Other Ingredients: 52%.
LifestageAdult, Puppy, SeniorAdultAdultAdultAdult
Breed SizeSmall Breeds, Medium BreedsLarge Breeds, Giant BreedsMedium Breeds, Large BreedsLarge Breeds, Giant BreedsSmall Breeds, Medium Breeds

Questions & Answers

37 Customer Questions

Why is the advantixII cheaper for extra large dogs than for large dogs? Doesn'tmake sense!!
Answer by heatherJul 15, 2022
It’s not, maybe you’re looking at different quantity amounts. 4 pack of XL is cheaper but not a 6 pack that this large dog one is comparable to.

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.

ReviewsWrite a Review

Rated 4.3847 out of 5 stars
1232 Reviews
Would recommend to a friend

1232 Customer Reviews

Rated 5 out of 5 stars
By Remy on Sep 24, 2022

Always the Best

Chewy gets a 5 star review in our home! Always the best in....products, customer service representatives, on time deliveries, prices are even lower that what I can purchase at area stores...we just love Chewy and would recommend it to everyone!

Rated 5 out of 5 stars
By aschaeff13 on Aug 23, 2022

Works great!

I've used K9 Advantix II on my dog for 3 years and I've never seen a single critter on him. Even once we were hiking and I found a tick on myself, yet he didn't have any on him! Read the instructions when applying also, this protect is meant to be applied from base of tail to top of neck, not just in one spot! And make sure to pair with a heartworm preventative!!! I get the ProHeart 12 month shot at my vet.

Rated 3 out of 5 stars
By Kati on Aug 27, 2022

Worked until it didn’t

I used this for a really long time and it always worked…until it didn’t. After a dose three days ago, I’m seeing fleas. Really upset that I’ll have to find something else.

Rated 5 out of 5 stars
By Ellie on Aug 23, 2022

Protect your dog, your best friend.

The reason I choose K9 Advantix II is because it works against mosquitos as well as fleas and ticks. I have used this brand since I rescued my furbaby in 2016.

Rated 5 out of 5 stars
By Debbie on Jun 28, 2022

This stuff works great

Advantix II works great for my 2 pups. Keeps them flea and tick free. I have not had any issues with pests since we have been using this product. We live in the country on 13 acres. So there are lots of critters that wander through. I want to make sure my pups are protected from fleas and ticks. Very pleased with this product.

Rated 5 out of 5 stars
By David on Jun 6, 2022

Works Great!

I usually use seresto collars for my dogs, but my standard poodle needed something else due to his hair type. It has worked wonderfully for us so far! My boy also accompanies me to work everyday to a doggie daycare/grooming salon and is around many different dogs - some of which inevitably have fleas. I’ve never seen a single flea on him, however.

Rated 2 out of 5 stars
By SueH on Jun 6, 2022

Have never had a problem with ticks using this product, until this year.

I have been using this product with great sucess for several years, and have always recommended it in the past. However, this year, I have already pulled 2 ticks off my dogs and the ticks were rather plump and still alive. Not very happy with this product this year. Has the formula changed? I haven't seen any fleas, so it gets 2 stars.

Rated 1 out of 5 stars
By horrible1 on Jul 19, 2022

A absolutely absurd.

Absolutely angry. Used this product and went on vacation. My one dog had fleas and my other dog got ticks. I want my money back I might as well not have used anything.

Rated 1 out of 5 stars
By Worthless on Jun 9, 2022

Does absolutely nothing

Both dogs still have fleas after 6+ months of use and fleas keep coming back. We've tried additional products to this flea medicine, but it's as though this flea medicine is doing absolutely nothing. This product does not work well. Very frustrating. Do not recommend

Rated 5 out of 5 stars
By Packager 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.