Advantage II

Written By Mel Lee-Smith
Published: 10/13/2020Updated: 08/30/2021
Advantage II for Dogs | Wag!

Advantage II for dogs is a topical treatment that kills fleas and chewing lice. Unlike some flea treatments that are absorbed into the dog’s bloodstream, Advantage II kills adult fleas on contact and prevents eggs and larvae from reaching maturity. Keep reading for more information on dosage instructions, cost, efficacy, frequently asked questions, and more.


The recommended dosage and application instructions vary depending on your dog’s weight. Advantage II for dogs comes in 4 dosage strengths and is available in quantities of 4 and 6 monthly treatments.

  • Advantage II for small dogs: 3 to 10 lbs

  • Advantage II for medium dogs: 11 to 20 lbs

  • Advantage II for large dogs: 21 to 55 lbs

  • Advantage II for extra large dogs: 55+ lbs

Advantage II is safe for dogs older than 7 weeks and weighing 3 lbs or more.

Dosage instructions

Applying Advantage II is easiest with your dog standing.

If your dog is between 3 and 20 lbs, part the fur between the shoulder blades to reveal the skin. Apply all the contents of the tube to the skin in one spot. 

If your dog is 21 to 55+ lbs, apply Advantage II evenly to the skin in 3 to 4 places along your dog’s spine. Work your way from between the shoulder blades to the base of the tail.

Reapply one tube every 30 days. Severe infestations may require more frequent treatment. If you believe your dog needs another treatment within a 30-day period, contact your vet first.


Some flea treatments are absorbed into the dog’s bloodstream. When fleas bite the dog, they ingest the poison and die off. Advantage II for dogs works differently, killing on contact and preventing unnecessary discomfort for dogs. 

Advantage II is also highly effective, killing fleas within 12 hours. Fleas living in the environment that attempt to reinfest the dog will die within 2 hours of contact. Advantage II protects dogs for a full 30 days. Adhering to the recommended dosage schedule is important to prevent reinfestation.


A 6-month supply of Advantage II for dogs is relatively inexpensive. Prices range from $35 to $50 on average for a package of 6 tubes.

Active ingredients in Advantage II

Advantage II for dogs contains 9.1% imidacloprid and 0.46% pyriproxyfen. Imidacloprid kills adult fleas, while pyriproxyfen prevents eggs and larvae from maturing. Both ingredients are highly effective and common in flea treatments.

Side effects

Side effects are rare but typically mild. Vomiting and diarrhea may occur following ingestion. Contact your vet if you notice any of the following side effects:

  • Redness of the skin

  • Excessive scratching

  • Vomiting

  • Diarrhea

  • Lethargy


Consult your vet before applying Advantage II if your dog is pregnant, nursing, or elderly. The effects of Advantage II last 30 days in healthy dogs, but may last up to 6 weeks in dogs with kidney disease or liver disease.

Drug interactions

Advantage II for dogs doesn’t interact with other drugs.

Allergic reactions and sensitivity

Allergic reactions to this medication are rare. If you notice the following symptoms of an allergic reaction, contact your vet immediately:

  • Hives or redness of the skin

  • Excessive scratching

  • Watery eyes

  • Labored breathing

  • Facial swelling

  • Anaphylactic shock

Frequently asked questions

I see fleas jumping on my dog. Is Advantage II working?

Yes. The active ingredients in Advantage II cause hyperactivity in fleas. If you notice fleas jumping around in your dog’s fur, that’s a good sign the treatment is working!

Is there a difference between Advantage II and Advantage Multi?

Yes. Both products are part of Bayer’s Advantage range. Advantage Multi also contains moxidectin, which treats several types of worms, as well as sarcoptic mange and microfilaria.

Does Advantage II for dogs kill ticks?

No, Advantage II does not kill ticks.

Can I bathe my dog or take them swimming after applying Advantage II?

Your dog can bathe or swim 24 hours after you apply Advantage II. Bathing or swimming sooner could wash off the product, rendering it ineffective.

Do I need to treat my home for fleas too?

Eggs and larvae living in your home and yard will continue to hatch and develop for 6 weeks. If these newly emerged fleas try to infest the dog, they’ll be killed within 2 hours. However, it’s a good idea to treat the environment for your own comfort. Other products in the Advantage range include sprays that kill fleas in carpets and upholstery.

What should I do if my dog licks Advantage II?

Supervise your dog until the product dries completely. Ingestion usually causes only mild symptoms like vomiting and diarrhea. However, if your pet ingests Advantage II, call your vet for advice, especially if they show signs of lethargy.

What do I do if I miss a dose?

Give the next dose as soon as you remember. Then, wait 30 days before applying the next dose. Never double up on doses or give more than one dose in a 30-day period. Setting a reminder on your phone or calendar can help you remember to give the dose on time.

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