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  6. K9 Advantix II XL Dogs Over 55 lbs. | Vet-Recommended Flea, Tick & Mosquito Treatment & Prevention | 6-Mo Supply

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K9 Advantix II XL Dogs Over 55 lbs. | Vet-Recommended Flea, Tick & Mosquito Treatment & Prevention | 6-Mo Supply Video

K9 Advantix II XL Dogs Over 55 lbs. | Vet-Recommended Flea, Tick & Mosquito Treatment & Prevention | 6-Mo Supply

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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 over 55 lbs. to use K9 Advantix II Extra Large Dog.

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

Key Benefits:

  • K9 Advantix II Extra Large Dog 30-day treatment & prevention protects dogs over 55 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.

Useful Information

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.

Customer Reviews

Review Summary
588 Reviews
85% (498)
10% (57)
2% (11)
2% (9)
2% (13)
96% Recommend this product (563 of 588 responses)
By Gera R.
K9 Advantix II XL Dog Flea, Tick & Mosquito Treatment
March 31, 2024
So far, so good! My German Shepherd and Rhodesian Hound both continue to scratch a bit. However, we've only just put the treatment on them two weeks ago. I give five stars without experiencing the time and impact fully yet. We are very happy with shipping, packaging, timeliness, good customer service. Thank you!!
By Stephanie Z.
Puyallup, WA
Best topical flea meds
March 16, 2024
Advantix is the only product I use on my dogs. The other 2 name brand topicals are completely inferior. I only wish they made something for cats this good.
  • Works better and longer than stated.
  • Offers protection for more than just fleas
  • It's a pesticide. In a perfect world I wouldn't have to use it or anything else at all
By Madelyn N.
Queens, NY
Recommended by Vet
December 23, 2023
My 8 year old Cavachon has been on this product all her life. Recommended by her vet due to her sensitive skin. Product has worked very well, and with no side effects.
  • Works well.
  • Expensive, but EntirelyPets offers a lower price.
By Edna
Desert Hot Springs, CA
Flea protection
August 6, 2023
Chanel has not been bothered by bites from fleas or any other insect while using this produce.
  • Easy to apply and works well.
  • no cons
By Dustin K.
Easy and Quick
July 30, 2023
Ordered the items for our three dogs with no issues. They arrived in a timely fashion with no mistakes.
By Barb
June 1, 2023
Have used this before, does a good job of protecting our dogs from fleas, ticks and mosquitos. I use on all three of our dogs, XL, medium, and small.
By Aric
Champaign, IL
This is a great product
August 30, 2022
I bought this for two lhasa apsos
  • Great for fleas, ticks, and mosquitos
  • Must keep purchasing overtime
By Kim
New york
Best price
August 7, 2022
Best price !
Always Works As Described
July 23, 2022
I'd give it full marks for efficacy, in other words, a full five stars. However, the price has escalated considerably over the years, far faster than most person's paychecks have done. If the product was available at a more reasonable price it would be so much more attractive. I've used it for years on multiple generations of my dogs and always been pleased by how well this product protects.
  • Simply put: it works
  • Simpy put: exorbitant price which has escalated much faster than overall inflation
By rochelle f.
prospect heights, Illinois
January 22, 2022
Exactly what we needed for our 5 dogs
By Rottie m.
Love this product used it for yrs.
October 17, 2021
Never had any issues with and bugs on my dogs. Love this product.
By Joe
It works!
August 26, 2021
K9 Advantix works very well for keeping fleas away and killing ticks that get on my dog. That's important to me, since I live in the country and we have armies of ticks in the spring and early summer. It's easy to put on which is good, since I have a wiggly dog to use it on. It's a little pricey, but worth it to keep the pests off.
  • Works on fleas
  • Works on ticks
  • Easy to put on
  • High priced
By Katherine
Millville, New Jersey
Works on large dogs too
August 8, 2021
About 20 minutes after application my dogs are absolutely flea & tick free. My dogs have plenty of woods and grass to venture in and they are free of pests.
  • Works fast and for 30 days.
  • Afraid to get them wet.
By Jennifer
Wasilla Alaska
It works!
June 1, 2021
I use this every year on my dogs
By Nancy
Great Buy
May 3, 2021
I live in Canada. Flea medication is so expensive here. I was glad this came across the border without any problems.
Works Great but Follow Directions
January 22, 2021
This works great when applied exactly as directed. Please read directions carefully and ask your vet if you have any questions so you will be sure to apply this product correctly. Note that this medication can be rendered ineffective if you give your pet a bath too close to applying this medication. I still prefer this medication over giving my pet a pill to take because she has a sensitive stomach.
  • Works if used as directed
  • Expensive
By Kathy g.
December 18, 2020
Great prices ...
  • Price
  • None
By Jim
Loveland, colo
life saver
September 11, 2020
k9-advantix 11 works perfectly for my country dogs, one of which has a life threatening reaction to even one tick. I have never had another episode on this poor guy by being diligent in regular use of this product on all five.
  • no ticks even as riders, in tick areas
  • none
By Mary
Gainesville, FL
Great price
August 31, 2020
Their prices on this product were the best.
  • Price
  • None
By Carol
San Jose Ca
Keeps my dog flea free
May 15, 2020
She doesn’t like the application process But is happy with the outcome!
By susan a.
Ashaway, RI
Advantix II
May 12, 2020
I use to use frontline, but didn't always work. I switched to Advantix II and have had no fleas or ticks on the dogs.
  • it works
  • sometimes causes a reaction
By Greg
East Freetown, MA
Heavily Wooded
April 13, 2020
We live in the “sticks” with a lot of deer ticks & in hotter weather, fleas. This protects our Choc Lab and us from being bothered by these pests. Thanks

Merchant Response:k9 Advatnix II, we trust it with our dogs too. Be safe!
  • Works like a charm
  • None
By Dottie
Somerset, Massachusetts
K9 Advantix II - Works Great!
April 7, 2020
I've been using K9 Advantix II on my 8 year-old Newfoundland since she was a puppy. So far I have never found a tick attached to her, thankfully.
  • Easy to apply once a month and it really works!
  • None
By Aric
Peoria, IL
Great flea/tick/mosquito preventative for dogs
April 4, 2020
This product is great. It works well to kill the fleas and ticks on the dog as well as prevent any additional ones. Not all flea and tick preventative topicals work on mosquitos but this one does.
  • Cheapest on EntirelyPets' website if purchased in larger quantities and the 15% discount is applied
  • Not very affordable for all people
By Granbygirl
Granby, MA
Great price
March 10, 2020
Fast shipping best prices. A win win
  • Proven product for New England
  • None
By Nancy
Warner Robins, GA
Flea control
February 22, 2020
Excellent product. My order was delivered quickly and accurately. All set for 1 year!
  • Effective flea control
  • Easy to use
  • None
By Stephanie
Puyallup, WA
Great product and great price!
January 18, 2020
Advantix always works for our fleas and outlasts the competition.
By Bev
Philadelphia Pa
Flea/ tick prevention
January 16, 2020
I've been using this for years on several of my dogs . I've actually seen bugs land on or near them & immediately fly off
  • Easy to apply & does what it says
  • Haven't seen any
North port, fl
January 16, 2020
Very easy to apply. Works as expected.
  • Easy to apply
  • Works at keeping my dogs flea free
North port, fl
January 16, 2020
Works great.
  • No fleas after 24 hours

Questions and Answers

2 Questions & 2 Answers
from Morrisville, Pa asked:
July 6, 2019
I have found 1 flea on my dog after using the product. Is this normal?
1 Answer
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.
Submitted by: Customer Service on October 8, 2019

from Sackville, Nova Scotia asked:
April 22, 2015
how many ml is in each application of K9advantixII for extra large dog? I have left over advantix for large dog (2.5ml) and want to use it up on a larger (extra large) dog.
1 Answer
Do not use left over doses on other dogs. This product is intended to have a full dose administer to each pet and should not be used in partial doses.
Submitted by: Customer Service on April 22, 2015