Warning: session_start(): open(/var/lib/php/sessions/sess_ihcp2qs4ig44tksrr6sdcm70t3, O_RDWR) failed: No space left on device (28) in /home/forge/fixfleas.com/public/wp-content/plugins/wp-custom-admin-bar/custom-admin-bar-functions.php on line 8

Warning: session_start(): Failed to read session data: files (path: /var/lib/php/sessions) in /home/forge/fixfleas.com/public/wp-content/plugins/wp-custom-admin-bar/custom-admin-bar-functions.php on line 8
Advantage II Side Effects on Dogs & Cats: Is Advantage II Safe?

Advantage II Side Effects

Better than the Original, or Still a Dud?


Are you trying to find a flea drop treatment that really works?

We’re going to take a look at Advantage II to see if it may be the spot-on treatment that will work for you.

How Does Advantage II Work?

There are two active ingredients in Advantage II. The first, imidacloprid (9.1%), is a neurotoxin that causes paralysis and death in the adult fleas. The second, pyriproxyfen (0.46%), is an insect growth regulator, or IGR. It keeps the flea eggs from hatching so that you don’t have a vicious cycle of re-infestation.

It comes in different doses based upon the weight of the dog.

What are Advantage II Side Effects?

The primary side effect of Advantage II is irritation at the site of administration. This should go away within a day or two but if it doesn’t, or if your pet is extremely disturbed by it, give him a bath in warm water to remove it. Call your vet if it doesn’t get better or if you pet exhibits any of the less common side effects listed below.

Though extremely rare with this product, side effects are possible and include:

  • lethargy
  • Hyperactivity
  • Drooling
  • Shaking
  • Poor Coordination
  • Excess vocalization
  • Hives or red skin
  • Hair loss at application site

Final Word

Advantage II has a high rate of user satisfaction and very few instances of side effects or allergic reactions. For these reasons, we feel comfortable giving a thumbs up to this flea drop. If you do happen to notice any odd behavior that you may believe to be a reaction, bathe your dog and call your vet immediately.

To save time and money, click here to find great deals on Advantage II online.

If you’ve tried Advantage II on your pet, please tell us about your experience in the comments section below.

9 Responses to “Advantage II Side Effects”
  1. Patricia says:

    The original Advantage was much better.Advantage 11 does not kill all fleas on dogs or cats Is it at all possible to get original Advantage? What is this lice problem? I’ve never heard of or experienced this issue.

  2. stella says:

    I usually put on advantage 20 and my 11lb papillon is find. I could not advantage 20 so I bought advantage 2 and one day after she was looking dazed, not wanting to be walking around, not peeing and pooping like normal. she was not drinking water. I had to force feed the fluids to get her too go. she would hold urine in until she went on blanket. took 4 days for her too be back too normal. the advantage 2 was the only think different I did and this was what happen. I bought 6 month supply and I guess now I will not use it on her and donate the 5 months to animal shelter. let me know is this a side effect.

  3. carol anderson says:

    5 yr. Old Yorkie poo ran around the house for about 45 min. After application of advantage II. Then kept drinking water.after about two hrs.she settled down but still not herself. I followed directions explicitly when I applied product. I am watching her carefully, if not completely herself tomorrow, will take her to vet.

  4. L Hoyt says:

    I put Advantage Ii on my dog on Sunday. He seemed fine unti Friday when he seemed to act scared. I didn’t suspect the flea medication at first as it was a full five days later. By Saturday he was not eating but he did drink water. We thought he just had a tummy ache. That evening he began vomiting and he became lethargic. On Saturday night he became very weak and he died Sunday morning. No warning! Our dog is a house dog and we do not believe he got into anything bad or poisonous. This was the first time to use Advantage….and our last. I have used other flea meducations and am aware of “how to apply” same. I also have cats. I’m having a hard time with the fact that I was trying to protect my pet and he is now gone so quickly. This medication does get into the blood stream of an animal and can very quickly kill them before you know it.

  5. Donna Elosser says:

    Having concern, about my cat after application. Scratching and biting at fur.
    ALOT…but he’s eating and drinking.
    Just wont quit SCRATCHING

  6. wisiv says:

    I have used Advantage on my Husky before with no side affects. This time I used Advantage2 on him about a week ago. He stayes under the cool porch all day and comes out at night when it’s not so hot to eat. A little over a week ago I applied Advantage 2 in the proper place for his weight. Today I went and found him laying in the yard and all of his hair from the application site all the way down his back was gone. It wasn’t pulled out or scratched out. Skin on back was white and unirritated in any way. I picked up a basically lifeless pet to move him to the shade out of the sun. I went in the house a talked to my wife about him. She went out later to check on him and he was dead. The only thing in his life that I changed was to use Advantage2 to kill fleas. Thanks Bayer for poisoning my family pet. Now I have to go bury him. He would have lived longer with the fleas sucking his blood. Maybe I could have helped him if I could have seen him earlier and got him to a vet or bathed him, but he was sick under the porch. So much for trusting Bayer, maybe they ought to just make aspirin, that’s pretty safe. By the way he still had fleas. Bayer killed my pet and not the fleas. I DON’T recommend Advantage 2 made by Bayer for any pet it’s apparently poison.

  7. Deborah mccormack says:

    I am very concerned about my Australian Shepherd. He’s nine years old, and put on the advantage II. On him, the next day he started with diarrhea, not eating or drinking, and throwing up. Until now we never put two and two together, he did the same thing last month. So what can we do with our dog, hate to see him so sick, and miserable. And I paid a great amount for the sith month supply, that I can no longer use. Deborah. And bandit

  8. tamara says:

    I looked up the side effects because our very perky 2 year old dog became very lethargic and just not himself for two or three days after treatment. WE WILL THROW AWAY the rest of the six month treatment!! HOW can a veterinarian, one charged with the care of pets, sell us this product??? DON”T BUY it!

  9. Tami says:

    Do not use!!! I applied this to my black cat, and now she has a bald spot the size of a quarter where I applied. I threw the rest of it away, and will never use again!!!

Tell Us What You Think!

Spam protection (register to skip this)

Time limit is exhausted. Please reload the CAPTCHA.