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 have a dog and two rats at home, can I use this on my dog even with the rats in the same home? I seen that it is dangerous for cats but not sure about other pets.

Answer by Chewy • May 29, 2018
K9 Advantix for Dogs (containing pymethrin), Advantage ll (containing pyriproxyfen) should not be used with or around rats due to increased toxicity.
Reviews
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4.5
Rated 4.5 out of 5 stars
4603 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

2152 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 Tim on Jan 4, 2026

Poorly packaged

All items were in a box with a 47# bag of dog food. The flaps were taped but not edges. The dog food squished other packaging. 2 of the Advantix boxes came open

All items were in a box with a 47# bag of dog food. The flaps were taped but not edges. The dog food squished other packaging. 2 of the Advantix boxes came open. 3 does fell out of the packing carton in gaps were the edges bulged.

Rated 5 out of 5 stars
By Kimberle on Dec 22, 2025

I buy this every year!

I have it on my calendar as a reminder to purchase enough for a year on Black Friday, I have three Aussie's and the savings and quality of this product helps me

I have it on my calendar as a reminder to purchase enough for a year on Black Friday, I have three Aussie's and the savings and quality of this product helps me be a better pet parent. We are "bug" free for another year. Thanks Chewy!

Rated 1 out of 5 stars
By Paul on Nov 30, 2025

Does not work very well!

My dog is still continuously scratching, I even applied a second dose after 3.5 weeks per advice from Elanco the manufacturer, and still the same results, still

My dog is still continuously scratching, I even applied a second dose after 3.5 weeks per advice from Elanco the manufacturer, and still the same results, still lots of fleas. I even have a pest control company that sprays my yard every two months! I would not recommend this product.

Rated 5 out of 5 stars
By MARYLEE on Dec 9, 2025

Effective Treatment

I have used it for each of my dogs for many years. I bought for Charlie and Stella most recently.Stella died so Charlie inherited her sippy of Advantix so I did

I have used it for each of my dogs for many years. I bought for Charlie and Stella most recently.Stella died so Charlie inherited her sippy of Advantix so I did cancel the recurring order as Charlie now works through Stella's 12 month supply.

Rated 5 out of 5 stars
By Courtney on Jan 7, 2026

Works very well!

My poor girl had fleas and I had tried everything over the counter. This medicine without a prescription worked quickly and my fur baby has no more fleas!

My poor girl had fleas and I had tried everything over the counter. This medicine without a prescription worked quickly and my fur baby has no more fleas!

Rated 5 out of 5 stars
By Sharon on Nov 10, 2025

Training treats that’s are awesome!

First of all, Elvis loves them. They can be broken into bite-size pieces so they last much longer. He is motivated to work for them, too. He knows when I get

First of all, Elvis loves them. They can be broken into bite-size pieces so they last much longer. He is motivated to work for them, too. He knows when I get out the bag that we’re going to work and is always ready and excited.

Rated 3 out of 5 stars
By Tracy on Dec 7, 2025

Works great if fur is not matted

Great on short-haired dogs. Longer haired dog was matted and groomer said she had fleas. Now that mats and fleas are taken care of it seems to be working again.

Great on short-haired dogs. Longer haired dog was matted and groomer said she had fleas. Now that mats and fleas are taken care of it seems to be working again.

Rated 3 out of 5 stars
By Jessica on Oct 20, 2025

Killed fleas but won’t use again

Used this on two dogs. One dog had no problems with it. It seemed to irritate the other dog’s skin - first time in 7 years I’ve had to use anti-lick spray to stop

Used this on two dogs. One dog had no problems with it. It seemed to irritate the other dog’s skin - first time in 7 years I’ve had to use anti-lick spray to stop dog from giving herself a hot spot. Not sure it’s was this but timing seemed to line up. Fleas were totally gone though.

Rated 5 out of 5 stars
By Erica on Dec 23, 2025

Effective flea and tick control at a reasonable price

Easy to apply, effective against fleas and ticks, doesn't irritate my dog's skin, reasonable price. My dog and I are both happy!

Easy to apply, effective against fleas and ticks, doesn't irritate my dog's skin, reasonable price. My dog and I are both happy!

Rated 5 out of 5 stars
By Pamela on Sep 8, 2025

Best Tick and Flea medication!

My Sam doesn't ever have ticks or fleas with this. She's getting older now and certainly slowing down but still comes out to the gardens and fruit trees with me

My Sam doesn't ever have ticks or fleas with this. She's getting older now and certainly slowing down but still comes out to the gardens and fruit trees with me always. She is still quite pleased when she corners a chicken who has escaped the run but now she just corners her and waits for me instead of plucking her butt feathers. Miss Kitty is very happy staying inside and this kibble has stopped her hairball problem. She also loves her treats at bedtime. Thank you for making it so easy for me to take care of those I love so much.