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K9 Advantix II Flea, Tick & Mosquito Treatment & Prevention for Medium Dogs

K9 Advantix II Flea, Tick & Mosquito Treatment & Prevention for Medium Dogs

4.3· 23,000 ratings

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$36.99at petfriendlysite.comObserved at 5:09 AM

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Our take on the K9 Advantix II Flea, Tick & Mosquito Treatment & Prevention for Medium Dogs

K9 Advantix II is a monthly topical flea, tick and mosquito treatment for dogs weighing 11 to 20 lbs. It combines imidacloprid to kill adult fleas, permethrin to repel and kill ticks and mosquitoes, and pyriproxyfen to stop flea eggs and larvae from developing. It is not for cats. The best new price is $14.95 at eBay as of November 4, 2026, a low entry point for a single dose, though multi-dose packs usually cost less per month.

Best forOwners of medium dogs (11–20 lbs) in tick or mosquito countryDogs that resist oral flea pillsHouseholds that want flea egg and larval control, not just adult killMonthly prevention during warm months
Pros
  • Three active ingredients cover fleas, ticks and mosquitoes
  • Kills all flea life stages, including eggs and larvae
  • Topical application avoids giving a pill
  • Waterproof after drying, so swimming and baths are fine
  • Starts killing fleas within 12 hours of application
Cons
  • Toxic to cats; keep treated dogs away from cats until dry
  • Permethrin can cause skin reactions in sensitive dogs
  • Needs 24 to 48 hours to dry before bathing or swimming
  • Monthly reapplication adds up over a season
  • Not for puppies under 7 weeks or dogs under 11 lbs

K9 Advantix II Flea, Tick & Mosquito Treatment & Prevention for Medium Dogs prices at every store

  • petfriendlysite.comNew

    In stock

    $36.99Observed at 5:09 AM
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  • eBayCheck price at eBay

K9 Advantix II Flea, Tick & Mosquito Treatment & Prevention for Medium Dogs price history

Lowest price we've seen: $36.99 on Nov 4 at petfriendlysite.com. Tracked across 1 store since Nov 4.

What reviewers say

With about 23,000 ratings averaging 4.3 out of 5, most owners report fewer fleas and ticks and say it works when other topicals failed. Complaints center on skin irritation at the application site and on cats in the home.

Pros
  • Clears fleas and ticks quickly
  • Long-lasting between monthly doses
  • Easy to apply along the back
Cons
  • Application-site irritation or hair loss on some dogs
  • Strong smell right after applying
  • Risk to cats that groom treated dogs

Specifications

Active Ingredients
Imidacloprid, Permethrin, Pyriproxyfen
Product Form
Topical
Pet Size
Medium
Pet Lifestage
7 weeks and older
Pet Weight
11-20 lbs

Questions and answers

Is K9 Advantix II safe for cats?
No. Permethrin is highly toxic to cats, so never apply it to a cat and keep treated dogs separated from cats until the product dries, usually 24 to 48 hours.
How often do I apply it?
Once a month. Each tube treats one dog for about 30 days, and you should not reapply sooner unless your vet says so.
Can I bathe my dog after applying it?
Wait until the application site is dry, typically 24 to 48 hours. After that the product is waterproof and normal bathing is fine.
What size dog is this for?
The medium size fits dogs weighing 11 to 20 lbs and at least 7 weeks old. Use the small size for 4 to 10 lbs and the large size for 21 to 55 lbs.
Is it cheaper to buy single doses or a multi-pack?
Single doses are the cheapest way to try it, like $14.95 at eBay as of November 4, 2026. A 4- or 6-month pack usually costs less per month if you plan to use it through the season.
How does it compare with oral flea pills?
It kills fleas, ticks and mosquitoes and stops flea eggs from hatching, which many chewables do not. The trade-offs are the drying wait and the danger to cats.
Where is the K9 Advantix II Flea, Tick & Mosquito Treatment & Prevention for Medium Dogs cheapest?
At petfriendlysite.com, for $36.99, as of our latest check.
What do buyers say about the K9 Advantix II Flea, Tick & Mosquito Treatment & Prevention for Medium Dogs?
Rated 4.3 out of 5 from 23,000 ratings.
Where can I buy the K9 Advantix II Flea, Tick & Mosquito Treatment & Prevention for Medium Dogs?
2 stores we checked sell it, including petfriendlysite.com, eBay.

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