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

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

4.3· 23,000 ratings

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$36.99at petfriendlysite.comObserved at 5:11 AM

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

K9 Advantix II is a monthly topical flea, tick and mosquito treatment for dogs. 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. The listing's weight range of 11-20 lbs conflicts with the large-dog label, so check the tube size against your dog's weight before buying. The best new price is $8.99 at eBay as of November 4, 2026, well below typical retail for a single large-dog dose.

Best forOwners of large dogs over 20 lbs who want mosquito protectionMulti-dog homes fighting fleas and ticksDogs that swim or get bathed often, since it is water-resistantBuyers who prefer topical over oral chews
Pros
  • Three active ingredients cover fleas, ticks and mosquitoes
  • Kills fleas at all life stages, including eggs and larvae
  • Water-resistant formula holds up to bathing and rain
  • Monthly topical application, no pill to hide in food
  • Widely stocked and often discounted per dose
Cons
  • Permethrin is toxic to cats, so keep treated dogs away from them
  • Weight range on this listing (11-20 lbs) does not match a large-dog product
  • Topical residue can transfer to furniture and hands
  • Some dogs show skin irritation at the application site
  • Not for puppies under 7 weeks

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

  • petfriendlysite.comNew

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    $36.99Observed at 5:11 AM
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  • eBayCheck price at eBay

K9 Advantix II Flea, Tick & Mosquito Treatment & Prevention for Large 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 fleas and ticks clearing within a day or two and lasting the month. Complaints center on application-site irritation and on cats in the household.

Pros
  • Fast knockdown of fleas and ticks
  • Lasts the full month for most dogs
  • Easy to apply along the back
  • Works well in tick-heavy areas
Cons
  • Skin redness or itching at the spot applied
  • Strong smell right after application
  • Cats in the home must be kept separate
  • Price per dose adds up over a year

Specifications

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

Questions and answers

Is K9 Advantix II worth it?
For dogs over 20 lbs in areas with ticks and mosquitoes, yes. It is one of the few topicals that also repels mosquitoes, and at $8.99 at eBay as of November 4, 2026 a single dose is cheap to try.
How does it compare with Frontline Plus?
Both kill fleas and ticks, but K9 Advantix II adds mosquito repellency through permethrin. Frontline Plus is safer around cats, so pick it if your dog shares a home with one.
How often do I apply it?
Once a month. Apply to the skin between the shoulder blades and do not bathe the dog for 48 hours afterward.
Is it safe around cats?
No. Permethrin is highly toxic to cats, so keep treated dogs separated from cats until the product dries, and never apply it to a cat.
Which tube size do I need?
Match the tube to your dog's weight: 21-55 lbs for large dogs and 55-88 lbs for extra large. The 11-20 lb range shown here is for small dogs, so confirm the size before ordering.
When is it cheapest?
Multi-dose packs and eBay listings tend to run below pet-store single doses. The current best new price is $8.99 at eBay as of November 4, 2026.
Where is the K9 Advantix II Flea, Tick & Mosquito Treatment & Prevention for Large 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 Large 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 Large Dogs?
2 stores we checked sell it, including petfriendlysite.com, eBay.

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