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

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About This Item

Details

  • 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.

Ingredients

Instructions

Size

FAQ

Learn More About K9 Advantix II From Our Team of Experts

About K9 Advantix II

K9 Advantix II Fights 5 Major Pests

K9 Advantix II protects against fleas, ticks, mosquitoes, biting flies, and lice. It kills fleas on dogs within 12 hours and continues to prevent infestations for 4 weeks. Do not use on cats.

How K9 Advantix II Works

The active ingredients in K9 Advantix II (imidacloprid, permethrin, and pyriproxyfen) spread over the skin. Fleas and ticks are killed through contact, so they don’t have to bite your dog to die.

Flea Treatment & Prevention

K9 Advantix II kills and repels fleas, ticks, and mosquitoes.

Kills & Repels

These flea drops kill adult fleas, flea larvae, and flea eggs to break the flea lifecycle.

Same-Day Effectiveness

K9 Advantix II kills fleas on dogs within 12 hours, and it keeps working for four weeks to prevent reinfestation.

No Prescription Needed

You don’t have to go to the vet to get quality flea and tick protection for your dog—simply buy and apply.

Fragrance-Free

This flea topical formula is fragrance-free and waterproof 24 hours after application.

Frequently Asked Questions

Can I use K9 Advantix II on My Dog?

K9 Advantix II is for dogs 7 weeks of age and older. This product comes in four sizes: Small Dog (4-10 lbs.), Medium Dog (11-20 lbs.), Large Dog (21-55 lbs.), and Extra Large Dog (over 55 lbs.). Choose the right size based on your dog’s weight, and do not use on cats.

How Do I Apply K9 Advantix II?

Break the seal on the tube, then part the hair along the top of your dog’s back and evenly apply the contents from the shoulder down to the base of the tail. The number of application spots will depend on the size and weight of your dog—refer to the product label for detailed instructions.

The Advantage Family

Get the Advantage over fleas with complete flea protection for your pet, home, and yard. The Advantage family of products has everything you need for a complete flea treatment and prevention plan, including monthly topical treatments, pet shampoos and sprays, household sprays for carpets and crevices, and even a yard and premise spray. Just be sure to get the right product for each need and use only as directed.

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Questions & Answers

27 Customer Questions

How do you apply the topical treatment? Is it messy?

Answer by Chewy • Mar 21, 2024
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.

How long do I need to wait before I can cuddle and pet my dog after using K9 Advantix II? How long do I have to wait to bush him and is that fur toxic?

Answer by Chewy • Aug 21, 2019
Once the treatment has been absorbed by the dogs' coat and they're fully dry, normally between 1-5 hours depending on the environment, the treated area should be safe for anyone to touch. It's always recommended to wash your hands after touching your pet.

Does this Kill ticks on contact

Answer by Chewy • Dec 14, 2019
K9 Advantix II kills fleas within 12 hours. New fleas that jump on the dog from the surroundings, such as grass, carpet and pet bedding, are killed within 2 hours with protection against further infestation for at least 4 weeks.

I know this product kills ticks, my question is does it specifically repel/ kill DEER TICKS. This is the only species of tick that carries Lyme disease and not all brands kill Deer ticks.

Answer by Chewy • Jul 01, 2020
K9 Advantix II repels and kills ticks including deer ticks, American dog ticks, brown dog ticks and long star ticks for up to 4 weeks.
Reviews
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4.5
Rated 4.5 out of 5 stars
4784 Ratings
Terms & Conditions

Customers Mention

Chewy identifies key considerations with the help of artificial intelligence and our veterinarians.

Ease of Use

84% Positive

Effectiveness

83% Positive

Ingredients

80% Positive

Long-Term Benefits

83% Positive

2198 Customer Reviews

Always consult a veterinarian about your pet’s health needs. Customer reviews should not be used as medical advice.

Rated 5 out of 5 stars
By Pat on Mar 28, 2026

Dog won’t take oral products

We used this when Lucy was a puppy, switched to Simparica and Nextgard for Lucy as she is a picky one. She started spitting it out nibbling pill pockets and meat

We used this when Lucy was a puppy, switched to Simparica and Nextgard for Lucy as she is a picky one. She started spitting it out nibbling pill pockets and meat wraps, spitting the pill out. So it’s back to Advantix II and Revolt for internal parasites. She has thick fur on her back, so challenging to apply.

Rated 5 out of 5 stars
By Geoff on Feb 15, 2026

hiking/water/trail worthy

we are avid hikers and campers and our dogs go with us everywhere. the risks of flea/tick disease are terrifying so our vet recommended this. We have never had a

we are avid hikers and campers and our dogs go with us everywhere. the risks of flea/tick disease are terrifying so our vet recommended this. We have never had a problem finding the *odd* tick or the dreaded infestation like we did with less pricey options. Easy to apply. we have never had an issue with a skin reaction (and one pup has skin issues) One dog is short haired, the second has long hair so we use a flea comb to part his mane for application. Very important to give it 48 hours before getting them wet in any way.

Rated 5 out of 5 stars
By Denise on Jan 22, 2026

No more ticks

Our 8y.o. dog & 5 m.o. puppy were getting ticks daily during a warm spell in December. After one application the first week of January the ticks are a thing of

Our 8y.o. dog & 5 m.o. puppy were getting ticks daily during a warm spell in December. After one application the first week of January the ticks are a thing of the past! And our dog and pup have had no bad reaction to this product. I've used it for years on dogs and have never witnessed a bad reaction after using K-9 Advantix II. Also, we have never had a case of fleas. Our dogs enjoy running loose outside where there are plenty of wild critters such as squirrels, rabbits, deer. etc. So our dogs have plenty of ops for picking up fleas & ticks this product also claims to repel mosquitoes which carry heart worms. So glad to note our dogs have never had a case of heart worms . I recommend this product !

Rated 1 out of 5 stars
By Elonda on Feb 7, 2026

4 orders paid for separately all in 1 box!!!! Not happy

Box was too heavy and crushed smaller items..you packed 4 bags of litter , cat food, and dog food, 2 boxes of flea control, 2 bottles of eye wash, treats into 1

Box was too heavy and crushed smaller items..you packed 4 bags of litter , cat food, and dog food, 2 boxes of flea control, 2 bottles of eye wash, treats into 1 box..it was too heavy and crushed smaller items. Those 4 orders were ordered separately and paid for separately. Why did you consolidate 4 paid orders of sensitive items????

Rated 1 out of 5 stars
By Lindsay on Mar 12, 2026

Adverse skin reaction

Unfortunately this gave my poor pooch a nasty rash that scabbed over. She has white fur, and I have heard that white dogs can have sensitive skin. I'll have to go

Unfortunately this gave my poor pooch a nasty rash that scabbed over. She has white fur, and I have heard that white dogs can have sensitive skin. I'll have to go back to oral preventives for her.

Rated 3 out of 5 stars
By Travice on Mar 12, 2026

Smelly

I think it's better than flea collars but the smell of the product on the dog is overwhelming. I've given her a couple baths to get rid of the chemical smell which

I think it's better than flea collars but the smell of the product on the dog is overwhelming. I've given her a couple baths to get rid of the chemical smell which is stron

Rated 5 out of 5 stars
By Jane on Feb 18, 2026

Just what my dog needed

There's another name brand flea & tick treatment that didn't work for my boy Maxwell, it was hard to watch those nasty bugs on him. Every since changing to K9 Advantix

There's another name brand flea & tick treatment that didn't work for my boy Maxwell, it was hard to watch those nasty bugs on him. Every since changing to K9 Advantix II we've had no problems at all ...almost 16 years now! :)

Rated 5 out of 5 stars
By Jeanne on Mar 8, 2026

The care and concern of your customer service employee, Elizabeth..

She understood my issue with Mindy, my dog, She offered a refund for the treats that were upsetting Mindy and suggested other treats that would be better for a

She understood my issue with Mindy, my dog, She offered a refund for the treats that were upsetting Mindy and suggested other treats that would be better for a delicate stomach.

Rated 5 out of 5 stars
By Monica on Mar 3, 2026

Easy to order and fast delivery!

It actually repels ticks, so Daisy doesn’t have to be bit before the tick will die. Why have ticks bite the dog and then die when medication actually repels them

It actually repels ticks, so Daisy doesn’t have to be bit before the tick will die. Why have ticks bite the dog and then die when medication actually repels them before they bite.

Rated 5 out of 5 stars
By Susan on Mar 13, 2026

Fast Shipping

I've started getting my flea meds and heartworm meds at Chewy. Very happy with selection of products, pricing, fast shipping and automatic reorder. Thank you!

I've started getting my flea meds and heartworm meds at Chewy. Very happy with selection of products, pricing, fast shipping and automatic reorder. Thank you!