Bayer K9 Advantix II Review: For Dogs (2020 Edition)

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So, you have heard about Bayer K9 Advantix II, and you want to know whether it is a reliable product which you can use on your dog or not, right?

Today, I’ll share the K9 Advantix II for Dogs review. In that, I’ll try to cover each and every question that comes to your mind. I’m very much sure that, at the end of this review article, you’ll get a clear idea of whether you should buy it or not.

And, in the end, I have also done a comparison between Advantix and Frontline Plus (the alternate product) to provide more helpful information.

Here is the quick review of Advantix II for Dogs for the impatient readers who just want to know the big points.

Quick Review of Bayer K9 Advantix II

Bayer K9 Advantix II Reviews

The Bayer K9 Advantix II is a non-prescription medication that you can use on your dog without the doctor’s prescription.

You have to apply it on the skin of your dog; it’s not a pill or injection. There are chemicals present in it, so, it’s not a natural flea killer & repellent.

The Company recommends that you should apply it once in a month to get the best result against the pests like fleas, ticks, and mosquitoes.

It really works, and therefore, the Company easily sold thousands of such products.

Do not use it on cats; it can be harmful to them.

So, with all these features, now Bayer K9 Advantix II is one of the most effective & popular flea treatment products for dogs.

K9 Advantix II for Dogs: Detailed Review

As told earlier, Bayer K9 Advantix II is a non-prescription medication that you have to apply on the skin of your dog.

It is highly effective in killing all the life stages of fleas, whether they are adult fleas, eggs or their larvae. Not only fleas, but it is also a very powerful weapon against ticks, mosquitoes, lice, and other biting flies.

For dog owners, the flea problem is the main cause of concern. These pests can cause many serious disorders like anemia, skin infections, dermatitis, and more.

The Company states that their product is so effective; it stops the fleas from biting in just less than 5 minutes, and within 12 hours it’ll kill 98% to 100% fleas on your pet.

Can be Used on Puppies (7 Weeks +)

Bayer Advantix II for Puppies

The Bayer K9 Advantix II for Dogs can be used on the puppies which are 7 weeks older, while if you purchase their rival product, Frontline Plus, for that your dog should be at least 8 weeks old.

So, if you have 7 weeks puppy, it is the best choice you can make.

Do Not Use It near Cats

Is K9 Advantix toxic to cats?

The ingredients present in it are toxic for cats. Therefore, even the Company recommends that you should not use it on cats. Even make sure, after the application of it, your dog stay away from your cat for at least the next 24 hours.

By getting contact with a recently treated dog, your cat can develop many harmful effects.

If you have a cat in your house, and it becomes difficult for you to maintain that security and safety measures, then I’ll recommend you should not buy it, because one single mistake can harm your little cat.

In that case, Frontline Plus can be helpful for you. Still, you have to protect your cat from that product. But, at least, Frontline shows less adverse effects on cats. In the below, you can also read the comparison & reviews of these two products.

What are the Ingredients?

What are the ingredients of Advantix II?

There are 3 key ingredients present in it. These are:

  1. Imidacloprid
  2. Permethrin
  3. Pyriproxyfen

I know, what you’re thinking.

Very Complicated Names, leave it; let’s move to the new section.”

But, don’t worry.

I’ll share the information about them in a very easy language.


Imidacloprid is an insecticide that effectively takes out fleas & other pests like termites, and it provides protection against them.

This chemical attacks on their nervous system and eventually kills them. After treating with Imidacloprid, its effects last for about 30 days, and it stays effective even after bathing.

According to a few studies, Imidacloprid is a perfect weapon, as 98 to 100% fleas die within 12 hours of treatment.


This is one of the most effective and key ingredients of this product. By the addition of this, flea treatment becomes even more effective.

It is also an effective insecticide for outdoor flea treatment like yard.

But, there is a catch!

Permethrin is toxic to cats.

Of course, the level of harm it can cause to cats depends on many factors like breed, age, diet, and immunity. But, it may include tremors, hyperexcitability, seizures, loss of balance & coordination, and even death.

According to PubMed, Permethrin toxicity in cats can lead to tremors, hyperexcitability, seizures, loss of balance & coordination, and even death.

Therefore, whether you are using Advantix or any other brand that contains Permethrin, make sure your cat does not get into contact with the product or with the recently treated dog.

If it is not practical for you to separate them for at least 24 hours, then I’ll recommend you to purchase any other flea treatment product that doesn’t contain Permethrin.


Pyriproxyfen is a pesticide that is used for flea control on pets, and for controlling pests like ants & roaches. You can also check the Pyriproxyfen General Fact Sheet shared by National Pesticide Information Center.

It is an insect growth regulator (IGR) that means; it prevents the larvae from reaching the adulthood, and thus stops them to reproduce.

Bayer K9 Advantix II Pros & Cons

There is no doubt that it is an excellent flea killer, and therefore, it is one of the most popular flea treatment products out there on the market.

But, still, it is important to discuss its pros & cons. So, let’s take a look to them.

Bayer K9 Advantix: Buy It or Not


  • It effectively repels and kills all stages of fleas, whether they are adult, larvae or eggs. Along with fleas, it is also very effective against ticks, lice, biting flies & mosquitoes.
  • Kills 98 to 100% fleas within 12 hours of application, and keeps working for a month.
  • It is water resistant and keeps working even after bathing.
  • It can be used on a 7 weeks old dog.
  • This is a reliable product. Trusted & tested by thousands of users.


  • This product is toxic to cats. Therefore, if you also have a cat, then make sure, you separate them for at least first 24 hours of treatment.
  • If you want a natural flea treatment method, then this is not for you. It contains chemicals.

K9 Advantix II Alternative

This is a great product, but this is not the only effective product out there, right?

What is the alternative to this product?

The biggest alternative & rival product is Frontline Plus by Merial. In the below, I have shared a detailed comparison and reviews of these two.

Frontline Plus for Dogs

Frontline Plus is the biggest rival of K9 Advantix.

It is able to kill 100% of adult fleas within 18 hours of treatment, and all the ticks within 48 hours.

Just like the Bayer’s product, it also kills all stages of fleas and provides complete protection.

You have to use once in a month, and it keeps working for 30 days.

But, what’s the difference between Frontline & Advantix?

The biggest difference is in their ingredients.

In the above product, there are 3 key ingredients. These are;

  1. Imidacloprid
  2. Permethrin
  3. Pyriproxyfen

While in the Frontline, there are two key ingredients that are different from the above.

  1. Fipronil
  2. (S)-Methoprene

The important point to consider is that Frontline doesn’t contain Permethrin (the ingredient that is toxic to cats).

But, still, don’t use it on cats.

And, Frontline doesn’t say anything about whether they repel mosquitoes or not, but Advantix clearly states that it works on mosquitoes also.

Another difference is that you can use Advantix on a 7 weeks old puppy, but for Frontline, your puppy should be at least 8 weeks old.

When Should You Buy Frontline Over Advantix II?

For Advantix, make sure, your cat stays away from a recently treated dog for at least 24 hours.

If you cannot provide that level of security & safety measures to separate your dog & cat, and if mosquitoes are not a big problem, then choose Frontline Plus for Dogs.

It can also be toxic to cats, but at least it’s not that dangerous.

The Final Verdict

There are many other good products out there, but Bayer K9 Advantix stands out from the crowd.

The few things that helped it to gain popularity are,

  1. Highly effective & it really works.
  2. Works on fleas, ticks, lice, mosquitoes, and other biting flies. Not all the products work on all these pests.
  3. Can be used on a 7 weeks old puppy, while average product recommends 8 weeks of puppy age.

And, yes it has some toxicity issues with cats.

But, if you do not own a cat, or you can separate them for first 24 hours, then I highly recommend Advantix II for Dogs.

So, have you bought this product or the alternative one before?

If yes, then what is your experience with it? Please share it in the comments.

1 Comment

  1. Kelly Alexander

    Frontline Plus Vs. K9 Advantix II.. Please read our true experience.. it may help you decide.
    Frontline Plus was a nightmare product. I’ve never seen anything like it. I gave this to our 2 yo Shi-Chi and it was almost like the infestation got worse! I am assuming because we assumed it would work. We continued to treat the home, bedding, yard etc. I guess we lost sight of treating the dog with this assumption. So the fleas got worse on her. After almost a month of this craziness. I did the internet search on Frontline plus and found we were not alone! According to other dog owners. Due to Frontlines popularity and excessive use. Fleas have become resistant to the main ingredients in Frontline Plus. It has been used with great success in the PAST. So we resorted to exposing my dog to another chemical treatment K9 Advantix II.
    Indeed it worked! My little buddy is sleeping comfortably again. Within the first 24hrs I’d say.. the fleas are gone. I stumbled on this article and thought it would be a great place to share. If anyone is hesitating between the two. Spend the extra for Advantix. Your best friend will thank you!!

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