K9 Advantix II for Medium Dogs 11-20 lbs, 12 Month | EP Rx
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K9 Advantix II Medium Dogs 11-20 lbs. | Vet-Recommended Flea, Tick & Mosquito Treatment & Prevention | 12-Mo Supply

Item# 5461618-12M
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$79.98Reg $103.99
$18.98Reg $24.99
$57.48Reg $74.99
$79.98Reg $103.99
$144.98Reg $188.99
$18.98Reg $24.99
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$79.98Reg $103.99
$144.98Reg $188.99
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  • Description
  • Ingredients
  • Directions
  • FAQ
  • Reviews


K9 Advantix II helps defend your dog against fleas, ticks, mosquitoes, biting flies, and lice. Simpler than a flea collar and troublesome pills, this vet-recommended topical formula works within 12 hours of initial application, killing adult fleas on contact to stop existing flea infestations and prevent new ones. Once K9 Advantix II is applied, your dog is ready to get right back to the things it loves most. K9 Advantix II pest protection is effective on both indoor and outdoor dogs. Your dog should be at least 7 weeks old and weigh 11-20 lbs. to use K9 Advantix II Medium Dog.

K9 Advantix II Medium Dog is a trademark of Elanco or its affiliates.

Key Benefits:

  • K9 Advantix II Medium Dog 30-day treatment & prevention protects dogs 11-20 lbs. from fleas, ticks, mosquitoes, biting flies and lice
  • Kills fleas within 12 hours of application
  • Vet-recommended formula kills & repels on contact so fleas don't have to bite your dog to die
  • Easy-to-apply topical treatment is fragrance-free and waterproof after 24 hours
  • No prescription needed


Active Ingredients % by Weight
Imidacloprid 8.80%
Permethrin* 44.00%
Pyriproxyfen 0.44%
Other Ingredients 46.76%
Total 100%

Two Proven Ingredients with Enhanced Activity

Imidacloprid and permethrin work together to overwhelm the nervous system of the parasite, providing neurotoxic activity beyond that of each compound alone. This leads to more profound and quicker insect paralysis and death.

Specifically, imidacloprid increases the efficacy of permethrin by activating insect nerve cells and increasing the frequency of neurotransmissions. As a result, more sodium channels are opened and the pyrethroid can interact much better with its target site.


Imidacloprid is an ectoparasiticide, an antiparasitic agent that targets parasites living primarily on the surface of a host. Chemically classified as a chloronicotinyl nitroguanidine, imidacloprid inhibits neurotransmitter transmission in insects, resulting in paralysis and death.


Imidacloprid exhibits both adulticide and larvicidal flea efficacy; it not only kills adult fleas and larvae on your pet, but it also kills larval stages in your pet's immediate surroundings.

Main Purpose

To kill fleas at all stages of their life cycles and stop them from being able to move or feed.


Permethrin is the additional ingredient in Advantix. It belongs to the Type I class of pyrethroid acaricides and insecticides, and it also acts as a repellent. Pyrethroids affect muscle and nerve cells' sodium ion channels by increasing their mean open time, which leads to hyperexcitability and death of the parasite.


Thanks to its repelling activity, permethrin reduces parasite bites and thus the risk of diseases and stress for your dog.

Main Purpose

To repel ticks, sand flies, and mosquitoes; to kill ticks and fleas.


Pyriproxyfen is a pyridine-based pesticide. A juvenile hormone analog, it interferes with the hormone signaling of growing insects, so that insects in immature stages are unable to mature. Additionally, a female insect that touches the toxin will produce eggs that will not hatch.


Pyriproxyfen provides an added layer of protection for pets and their surroundings. It interrupts the flea life cycle at multiple stages, halting the growth and development of insect eggs and larvae and preventing re-infestation.

Main Purpose

To prevent flea eggs from hatching and larvae from growing.


Applying K9 Advantix II to your pet is a fast and easy process. First, remove the K9 Advantix II applicator tube from its packaging and use scissors to peel down the foil. Next, hold the applicator tube in an upright position and pull the cap off the tube. Use the upturned cap to break the protective seal, and you're ready for application.

For easiest application, your dog should be standing upright. Evenly apply the entire contents of the K9 Advantix II tube to two or three spots from the back of the shoulder to the base of the tail. Part the hair at each spot until the skin is visible, then place the tip of the tube on the skin and gently squeeze out a portion of the solution. Be careful not to apply an excessive amount of the solution in any one spot, otherwise some of the solution might run off the side of your dog. Dispose of the container and do not reuse or refill. Do not empty unused product in any indoor or outdoor drain.

For optimal control and prevention of parasites, use K9 Advantix II every month. K9 Advantix II is available in four- and six-month supplies. Do not use K9 Advantix II on cats or any animals other than dogs.

Application Instructions: Evenly apply the entire contents of the tube to four to six spots on the top of the back--from the shoulder to the base of the tail. Apply monthly.

Length of Effectiveness: Under normal conditions, the product is effective for one month. However, in cases of severe flea infestation, re-treatment may be necessary earlier than four weeks. Do not retreat more often than once every seven days. After flea control is attained, return to a monthly re-treatment schedule.

Hazards to Humans: Causes eye irritation. Harmful if swallowed. Do not get in eyes or on clothing. Avoid contact with skin. Wash hands thoroughly with soap and warm water after handling.

Hazards to Domestic Animals:

*For external use on dogs only. *Do NOT use on animals other than dogs. *Do NOT use on puppies under seven weeks of age.

Do not get this product on dog's eyes or mouth. Consult your veterinarian before using this product on debilitated, aged, pregnant, or nursing animals. Individual sensitivities, while rare, may occur after using any pesticide product for pets. If signs persist, or become more severe, consult a veterinarian immediately. If your animal is on medication, consult your veterinarian before using this product.

Do Not Use on Cats: Due to their unique physiology and inability to metabolize certain compounds, cats must not use this product. If applied to a cat, or ingested by a cat that actively grooms a recently treated dog, this product may have serious harmful effects. If this occurs, contact your veterinarian immediately.

Environmental Hazards: This product is extremely toxic to fish. Do not add directly to water. Do not contaminate water when disposing of product or package.

    First Aid: Have the product container or label with you when calling a poison control center or doctor, or when going for treatment.

    If in eyes: Hold eye open and rinse slowly and gently with water for 15 to 20 minutes. Remove contact lenses, if present, after the first 5 minutes, then continue rinsing eye. Call a poison control center or doctor for treatment advice.

    If swallowed: Call poison control center or doctor immediately for treatment advice. Have person sip a class of water if able to swallow. Do not induce vomiting unless told to do so by the poison control center or doctor. Do not give anything by mouth to an unconscious person.

    If on skin or clothing: Take off contaminated clothing. Rinse skin immediately with plenty of water for 15 to 20 minutes. Call a poison control center or doctor for treatment advice.

    To physician: Treat patient symptomatically.

Keep out of reach of children.


Where can I buy K9 Advantix II?

K9 Advantix II does not expire.

How long does K9 Advantix II last?

A single application of K9 Advantix II keeps working for a month. It is safe to re-apply the product more frequently but this is rarely required.

How often should I allow my dogs to swim when using K9 Advantix II?

Dogs can swim as much as they like while treated with K9 Advantix II. Please wait a minimum of 48 hours after product application before they get wet to ensure the product has dried and spread across the skin.

When can I bathe my dog after application of K9 Advantix II?

Bathing of pets is not required, however if you are bathing your pet, use an appropriate shampoo. A non-medicated shampoo made for dogs is fine. Baths can be given as often as once per month without affecting the performance of the product. If more than one bath is given, the product should be reapplied after the second bath.

Flea shampoo, medicated shampoos, human shampoo and dish detergents are not appropriate choices when managing fleas with K9 Advantix II and may affect the performance of the product. Please wait 48 hours between product application and bathing.

How long should I wait to apply K9 Advantix II after bathing my dog?

Apply K9 Advantix II after the dog’s coat has dried. We recommend waiting 48 hours after a bath before applying K9 Advantix II to allow the natural oils to return to the dog's skin.

When using K9 Advantix II, what type of shampoo is recommended?

A gentle pet shampoo is compatible with K9 Advantix II. Flea shampoo, medicated shampoos, human shampoo and dish detergents are not appropriate choices when managing fleas with K9 Advantix II and may affect the performance of the product.


Review Summary
37 Reviews
76% (28)
22% (8)
0% (0)
0% (0)
3% (1)
97% Recommend this product (36 of 37 responses)
I use it all of the time
October 25, 2023
Great deal
By Nancy D.
N J Shore
It works!
July 22, 2023
We’ve been using this for years, and haven’t seen a flea and hardly any ticks in all that time. It really works!
  • It works really well and is easy to apply.
  • Quite pricey
By Julie
Louisville, KY
Great product
March 8, 2023
I've been using this for years and years on all my dogs. They love the flavor and take them with no problem. Got my product super fast!
By Mike o.
Cedar Falls, IA
December 22, 2021
They work well for my dog and have since he was a puppie, 14 yrs old now.
By Aric
Champaign, Illinois
Great product that protects against fleas, ticks, and mosquitos
September 16, 2021
I have been using this product for years. It is the only one I could find that would protect my dogs from mosquitos in addition to fleas and ticks. However, this is super dangerous for cats. If you have one more more cats that cuddle or come into close contact with your dog(s), make sure you do NOT allow that to happen for at least a few days after using this product.
  • Great for protecting dogs against fleas, ticks, and mosquitos.
  • Terribly dangerous for cats and could have severe consequences if applied to a cat or if a cat is allowed to come into close contact with a dog after using this product.
By Jennifer C.
Eatonton, GA
Excellent Product
August 16, 2021
We have been using this on our two lab mix girls for years and it has done a great job for us. I know there have been other products introduced in recent years but we just stick with K9 Advantix II. No reason to change if it works.
By Nicole
Long Island NY
July 18, 2021
I purchased 2 years worth for my 2 Springer Spaniels. Unfortunately the return policy is 30 days from purchase. I'm 60 days in. I've tried 2 applications and I find fleas all over my dogs. This stuff doesn't work at all. Not satisfied. Will never purchase again. I do not blame entirely pets. I actually love the company.
  • Does not do a thing to combat or prevent fleas.
By Louise
Athens, Ga
Best price for Advantix II
May 19, 2021
This product works best against fleas and ticks on our dogs. Best price I found on internet.
By Art D.
Mays Landing, NJ
Best Price, Quick Shipping
May 7, 2021
If you have been looking for K9 Advantix II for your little friends at the best price possible, here it is. I searched many, many websites looking for the best price and found it on EntirelyPets. Ordering was easy, and shipping was very fast.
You can't go wrong!
  • Best price
  • Very fast shipping
  • None
By Jules
Louisville, KY
Great product
May 6, 2021
I've been using this for years with all my dogs. Never had any side effects and they love the taste.
By Robin L.
May 3, 2021
good product
By Ken
Advantix ii
December 31, 2020
The only topical that i use and is effective. All my canine get this formula when full grown
By Joan
Western Massachusetts
November 25, 2020
All good. Arrived quickly and a great price.
By Kleid
Wonderful product
October 22, 2020
I have three dogs and this product is great. Ordering was a smooth process and fast shipping. I would recommend this to everyone. Thanks
By Brittany
South Carolina
Works Phenomenal
September 23, 2020
I have tried everything and this product works!
By Basset m.
Rougemont, NC
What a deal!
September 5, 2020
I look Online for the best deal on flea and tick products I use for my dogs. And with 5 basset hounds, why pay more than you have to. I was delighted to find K9 Advantix II so reasonable. I don’t know how other sites can charge so much more for the same thing. I will definitely be shopping here again.

Merchant Response:We are glad to have you Basset M. If there is anything more we can do for you just give us a call.
By Mac
Long time use
August 16, 2020
My veterinarian proscribed this a long time ago. I've been using it on my dogs ever since. Have had no problems with fleas or ticks
By Kathy
Hot Springs, Ark.
K9 II advantix
May 20, 2020
Great product and works well. I use it for my 3 dogs and it is great!
By Ness
Rockingham Virginia
Very pleased!
May 10, 2020
The price was great! Quick shipping! I will definitely shop here again!
By John
Roundhill, KY
Great buy Advantix II
April 23, 2020
The product we use regularly, but the deal from Entirely Pets was super.
By Carolyn M.
3538 holiday lake drive holiday fl
Excellent purchase
April 3, 2020
One of the few products I could find that treated fleas ticks AND MOSQUITOS.

TOPICAL I thought it was going to be a chewable.

Delivery took about a week. Works well on my 63 lb. dog (considered X-Large). No problems.
Make sure to get it on the skin under the fur. Very well priced, vet is much higher.

Thank you.
By Will
Great! Thanks!
March 2, 2020
Arrived as promised! Thanks!
By Michelle C.
Lubbock, TX
4 month K9 Advantix II Blue for XL Dogs
September 6, 2018
Excellent and quality product for the best price I'v found on-line or in store.

Merchant Response:Michelle, you are too kind! Thank you. %uD83D%uDE0A
  • Great price /Fast shipping
By Armand M.
Best protection for your pets
August 30, 2018
Protects your pet from fleas, ticks and mosquitoes. Great reputation and the product works as advertised.
By Janet
Mystic, Connecticut
"It Works"
June 7, 2018
We've been using K9 Advantix II Blue for years. Never any kind of bug on either of our Goldendoodles. Sure wish I could get a product at that price, works that well, and not be greasy on my two beautiful Golden beauties.
By Donna R.
K9 Advantage Blue
May 31, 2018
Quick purchase and delivery!
By Julia
Brockton, Massachusetts
It works
April 4, 2018
I've used this product for my boerboel for over 5 years - she's 6 yrs old and 140# - lol! It works and she has no reaction to it.
By "Glenda"
Zachary, La.
K9 Advantix
February 2, 2018
Please with the shipping and Service...Also pleased in the Prices..Thank You!!!
  • Service Excellent.....Prices also...
  • NONE!!!!
By Deanna B.
Slinger, wi
A Very good price
December 3, 2017
very happy with your service.

Merchant Response:Thank you for your kind words Deanna, glad we could help!
By Sue
Carlisle, OH
This is my go to brand for taking care of fleas+mosquitos
September 15, 2017
I've used this particular brand for many years with great success!

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