K9 Advantix II Flea & Tick Spot Treatment for Dogs, 11-20 lbs, 6 Doses (6-mos. supply)

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About This Item

Details

  • Helps to protect dogs weighing 11 to 20 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
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

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

22 Customer Questions

Can I pause this ?

What's the expiration date? I can't find it on the box?

Answer by Chewy • Mar 19, 2018
This product does not have an expiration date. It will be safe to use as long as you store unused containers in their original packaging and at room temperature.

I see a lot of reviews for fleas but I have a trouble with ticks. How good is this at preventing and killing ticks?

Answer by Chewy • Mar 13, 2018
This product repels and kills ticks including Deer ticks, American dog ticks, Brown dog ticks, and Lone Star ticks for up to 4 weeks.

does it kill the eggs and mosquitos

Answer by Chewy • Mar 25, 2018
The Treatment kill fleas of all stages and also repels and kills mosquitoes.
Reviews
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4.5
Rated 4.5 out of 5 stars
3668 Ratings
Terms & Conditions

Customers Mention

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

Ease of Use

82% Positive

Effectiveness

82% Positive

Ingredients

81% Positive

Long-Term Benefits

84% Positive

1606 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 Jackie on Jan 11, 2026

Works!

This eliminates fleas and keeps them from returning! My dog is indoors, except for walks and potty breaks. Somehow she still gets fleas. I regularly use these drops,

This eliminates fleas and keeps them from returning! My dog is indoors, except for walks and potty breaks. Somehow she still gets fleas. I regularly use these drops, no more problems! Chewy is always in stock, fast and dependable!

Rated 3 out of 5 stars
By Florena on Jan 8, 2026

Does it irritate?

My dog hates it when I apply this. He will leave the room and find something he can roll on to get it off him. The bathroom carpet or the carpet in the basement

My dog hates it when I apply this. He will leave the room and find something he can roll on to get it off him. The bathroom carpet or the carpet in the basement. I wonder does it irritate his skin? Why does he try to get it out of his fur?

Rated 5 out of 5 stars
By Mae on Dec 31, 2025

Works well!

Our dog knows when we open up the package it’s time for her to get her treatment. She jumps up on the sofa, bends her head down and waits for us to apply her monthly

Our dog knows when we open up the package it’s time for her to get her treatment. She jumps up on the sofa, bends her head down and waits for us to apply her monthly flea and tick preventative to her neck!

Rated 1 out of 5 stars
By Roy on Dec 18, 2025

Chewy fails

Chewy has repeatedly failed in their promises. They tell me as they will you the I am the best part of Chewy. I choose to not do business with a company that does

Chewy has repeatedly failed in their promises. They tell me as they will you the I am the best part of Chewy. I choose to not do business with a company that does not honor their promises. You can be sure they won't post this review.

Rated 3 out of 5 stars
By Carol on Dec 5, 2025

Not Great

It’s not the best flea remedy on the market. I’d rather work with “Only Natural Pet”. There’s a small metal tag that attaches to their collar. Wards off fleas, ticks,

It’s not the best flea remedy on the market. I’d rather work with “Only Natural Pet”. There’s a small metal tag that attaches to their collar. Wards off fleas, ticks, mosquitoes for approximately one year. I hate putting those chemicals on my dog.

Rated 5 out of 5 stars
By Maylene on Jan 16, 2026

Quick delivery

No side effects compared to the oral flea and tick meds. I feel safer with this Flea and Tick treatment. My vet suggested rgis and CHEWY delivers!

No side effects compared to the oral flea and tick meds. I feel safer with this Flea and Tick treatment. My vet suggested rgis and CHEWY delivers!

Rated 5 out of 5 stars
By Suzette on Nov 12, 2025

Good for Florida

We have tried everything and this product has been great. Florida is notorious for flea resistance to other products. This seems to work for my yorkies. The nexgaurd

We have tried everything and this product has been great. Florida is notorious for flea resistance to other products. This seems to work for my yorkies. The nexgaurd caused seizures in two of my guys so never again with that. Topical is good as long as you stay on a strict monthly schedule.

Rated 1 out of 5 stars
By Ann-Bettina on Oct 15, 2025

Useless product

I switched to this topical flea medication from Nexgard chews because my senior pup has had many teeth removed and couldn’t get the shoes down. I’m so frustrated

I switched to this topical flea medication from Nexgard chews because my senior pup has had many teeth removed and couldn’t get the shoes down. I’m so frustrated because K9 Advantix i has proven to be absolutely useless. My poor animal is chewing himself raw from fleas daily and I am constantly picking a half a dozen fleas off of his body at any given time.. I’m upset because I had ordered this using auto ship and now have a huge supply of this useless product!

Rated 1 out of 5 stars
By Doris on Jan 2, 2026

Waste of money in central Florida

After using this K9 Advantix 11 they have more fleas and ticks than they ever did. I even got a tick on me! I wish I had not bought a 3 month supply!

After using this K9 Advantix 11 they have more fleas and ticks than they ever did. I even got a tick on me! I wish I had not bought a 3 month supply!

Rated 3 out of 5 stars
By Phyllis on Nov 5, 2025

Minor redness

This is the only over the counter flea and tick I have found for my sensitive maltipoo. It leaves reddish outbreak on her back for several days but not a scaly rash

This is the only over the counter flea and tick I have found for my sensitive maltipoo. It leaves reddish outbreak on her back for several days but not a scaly rash. I give her Benadryl and the rash leaves after several days. I don't know what other alternative I have to protect her from fleas.