K9 Advantix Flea, Tick & Mosquito Prevention for Large Dogs, 21-55 lbs, 2-Monthly Treatments

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About This Item

Details

  • K9 Advantix for large dogs is ideal for dogs ages seven weeks and older weighing 21–55 pounds.
  • Formulated to protect your pup from fleas, ticks, mosquitoes, biting flies, and lice for 30 days per treatment.
  • Works on contact to kill and repel fleas on dogs within 12 hours of application even without a bite.
  • This easy-to-apply topical treatment is fragrance-free and waterproof after 24 hours.
  • K9 Advantix offers fast relief—no prescription needed.

Ingredient Information

Instructions

K9 Advantix for Dogs

K9 Advantix, from the Advantage brand, prevents and treats fleas, ticks, mosquitoes, biting flies, and lice on dogs. It works through contact to kill fleas on dogs within 12 hours of initial application. Do not use on cats.

One Application Protects for 30 Days

This once-a-month topical flea and tick treatment is easy to apply, and the fragrance-free formula is waterproof after 24 hours of application. Plus, K9 Advantix is available without a prescription, so you don’t have to go to the vet to get it.

How It Works

K9 Advantix kills fleas through contact. It also kills and repels mosquitos and ticks, kills lice, and repels biting flies. Apply K9 Advantix to your dog once every 30 days according to the complete directions for use on the product label.

Find the Right Dose for Your Dog 

Your dog should be at least 7 weeks old to use K9 Advantix. It comes in four sizes, according to your dog's weight: Small Dog (4-10 lbs.), Medium Dog (11-20 lbs.), Large Dog (21-55 lbs.), and Extra-Large Dog (over 55 lbs.). Use as directed by label.

About Advantage

The Advantage family of products has what 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.

Shop Advantage

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Reviews
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4.4
Rated 4.4 out of 5 stars
438 Ratings
Terms & Conditions

Customers Mention

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

Ease of Use

82% Positive

Effectiveness

80% Positive

Ingredients

80% Positive

Long-Term Benefits

80% Positive

135 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 Crazy on Dec 29, 2025

Didn’t work

I have 6 dogs all six got this medication to protect them against fleas yet a few of them seem to have no effect after medication was administered and still continue

I have 6 dogs all six got this medication to protect them against fleas yet a few of them seem to have no effect after medication was administered and still continue to itch and I can still see flea bites on their skin

Rated 4 out of 5 stars
By Twana on Dec 13, 2025

Good product

I find it works well. My problem is with shipping. I ordered this via auto ship with bagged dry animal food and they throw the meds inside and it then is crushed

I find it works well. My problem is with shipping. I ordered this via auto ship with bagged dry animal food and they throw the meds inside and it then is crushed when it arrives. So the product is great but shipping is bleh.

Rated 5 out of 5 stars
By Kristina on Oct 16, 2025

Works when you’re consistent.

Hadn’t had a problem with fleas in years since we had a stray cat overpopulation issue. I had to bomb their sleeping area with Diatomaceous Earth and flea bath them

Hadn’t had a problem with fleas in years since we had a stray cat overpopulation issue. I had to bomb their sleeping area with Diatomaceous Earth and flea bath them and applied these when they were fully dry. I know there are still fleas in the area because neighbors complain about it with their dogs but I haven’t had any issues since I started using K9 Advantix every month. It’s inexpensive and doesn’t leave an oily film on their fur like some other topical treatments. I recommend it to anyone who needs it.

Rated 2 out of 5 stars
By Kathy on Dec 19, 2025

Found out too late

Packaging says 55+. Remi is at least 100 lbs and this dosage was not effective. Found out later it is offered for Extra Large dogs but will have to wait to use until

Packaging says 55+. Remi is at least 100 lbs and this dosage was not effective. Found out later it is offered for Extra Large dogs but will have to wait to use until this product wears off.

Rated 4 out of 5 stars
By L on Sep 8, 2025

Seems to work better than some

The Advantix seemed to work well the first week and a half after I used it on my dog before I found fleas on him again. Compared to two other brands that didn't

The Advantix seemed to work well the first week and a half after I used it on my dog before I found fleas on him again. Compared to two other brands that didn't even seem to last that long, this was better. I'm not sure if it was because the fleas are extra resilient this summer or what, but it's been brutal keeping them off of both my dog and cat. But I don't want to put any stronger chemicals on them so I'm combing and using natural oils as well, to keep them flea-free for the next couple of weeks until I reapply, which will hopefully keep the fleas away until fall arrives and the fleas go away!

Rated 5 out of 5 stars
By Christina on Dec 2, 2025

Works

I wished I picked the K9 advantage over frontline for my cat as she has no fleas but my cat still does but I may have got the wrong weight

I wished I picked the K9 advantage over frontline for my cat as she has no fleas but my cat still does but I may have got the wrong weight

Rated 3 out of 5 stars
By Megan on Nov 10, 2025

Tolerable spot on

This product doesn't irritate my dogs' skin. Unfortunately, this year, our fleas are resistant to Advantage. Normally, I really like Advantage.

This product doesn't irritate my dogs' skin. Unfortunately, this year, our fleas are resistant to Advantage. Normally, I really like Advantage.

Rated 5 out of 5 stars
By Laurie on Jan 12, 2026

It works!

Works as good as the flea medicine I get from my vet at a much higher price.

Works as good as the flea medicine I get from my vet at a much higher price.

Rated 2 out of 5 stars
By Toni on Sep 12, 2025

Caused Reaction for My Dog

I’m giving this two stars since the ease of use and price of this product are convenient, however, my dog has been miserably itchy since we put the medicine on her

I’m giving this two stars since the ease of use and price of this product are convenient, however, my dog has been miserably itchy since we put the medicine on her. She developed dandruff along her back where the medicine was applied and has red patches all over her stomach.

Rated 5 out of 5 stars
By Elizabeth on Jan 18, 2026

Works well

This cream helps dry and clean the wetness inside my dogs wrinkle

This cream helps dry and clean the wetness inside my dogs wrinkle