Advantage®, K9 Advantix® II, and Advantage® Multi

PetMD’s medications content was written and reviewed by veterinary professionals to answer your most common questions about how medications function, their side effects, and what species they are prescribed for. This content shouldn’t take the place of advice by your vet.

What Is Advantage®?

Advantage^®  is a series of medications used to treat and prevent flea infestations in cats and ferrets and fleas and lice in dogs. Advantage® is effective against adult fleas and flea larvae. It is available in several formulations (in combination with other medications) and strengths. Use only specific Advantage^® products as advised by your veterinarian.  

Advantage Multi^® includes the medication moxidectin, which adds heartworm, hookworm, and roundworm prevention to Advantage^® for dogs and cats. Advantage Multi^® for cats also provides protection against ear mites, while in dogs, Advantage Multi^® also protects against whipworm and sarcoptic mange. It is available only by prescription. Talk to your vet about whether Advantage Multi^® is right for your pet. Always read and follow all label instructions carefully.

K9 Advantix^® II is used only in dogs to treat, prevent, and repel fleas, ticks, lice, mosquitoes, and biting flies. It contains permethrin, which is not safe for use in cats.

These medications are dosed separately for dogs and cats and given by weight, so it is important to use the correct species and sized medication for your pet. Using cat medications on dogs or using dog medications on cats can cause serious problems, including lack of efficacy or an overdose.   

How Advantage®, K9 Advantix® II and Advantage Multi® Works

The main ingredient in the Advantage line of products is imidacloprid, which works by blocking certain naturally occurring chemicals found in parasites that are responsible for sending nerve signals. Imidacloprid disrupts their central nervous system and causes death of the parasite. When used as a topical product, imidacloprid does not enter your pet’s bloodstream.

The second active ingredient in Advantage^® and K9 Advantix^® II products is pyriproxyfen, which mimics a growth hormone that naturally occurs in parasites. Pyriproxyfen targets young and immature parasites by preventing them from growing into adulthood. It can also prevent egg production in female insects.

K9 Advantix^® II also contains the ingredient permethrin, which works similarly to imidacloprid. Permethrin blocks certain chemical messengers in ticks and overwhelms their nervous system, causing paralysis and death.

Permethrin is toxic to cats; K9 Advantix^® II should never be used in a cat. Cats should not be allowed around dogs treated with K9 Advantix^® II within the first 24 hours of application.

Advantage Multi® products also contain the ingredient moxidectin, which shifts chloride, a naturally occurring electrolyte, across the cell membrane of certain susceptible worms such as heartworms, roundworms, and hookworms. By overloading chloride into these worms, it affects the electrical activity within their nervous system, causing muscle paralysis and death.

Advantage®, K9 Advantix® II and Advantage Multi® Directions

Follow the directions on the drug label of the species-specific product or as provided by your veterinarian. These topical products should be applied to the skin after the fur has been parted.

In cats and ferrets, medication should be applied to one area at the base of the head. When using K9 Advantix^® II, it is applied in 2-3 equal spots along the back, from the shoulders to the tail. Advantage Multi^® is applied in 3-4 equal spots along the upper back to the base of the neck in areas where your pet is unable to lick.

Missed a Dose?

If you forget to give a dose of Advantage^®, K9 Advantix^® II, or Advantage Multi^®, give it when you remember. Most of these medications are given once a month and the schedule should follow as close to 30 days as possible in between dosages. If your veterinarian has directed you to give this medication on a different dosing schedule, contact them for further instructions if a dose was missed.

Advantage®/K9 Advantix® II/Advantage Multi® Possible Side Effects

Side effects with any of the topical Advantage/Advantix products include:

• Itching, redness, or irritation at the site of application

• Drooling

• Vomiting

• Diarrhea

Additional side effects that may be seen with Advantage Multi^® include:

• Lethargy

• Loss of appetite

• Hyperactivity

Additional side effects that may be seen with Feline Advantage Multi^® include:

• Lethargy

• Agitation

• Excessive grooming

• Irritation at the application site: scratching, rubbing, or shaking

• Increased thirst

Human Side Effects

This medication is not for use in humans. It is recommended to wash your hands after administering this medication, as this medication is harmful to humans if swallowed or absorbed through the skin. Likewise, this medication may cause substantial but temporary eye injury. Do not allow children to come into contact with animals being treated with these medications until the application area is completely dry. If you accidentally ingest a pet medication, have a skin reaction to this product, or get this product in your eyes, please call your physician or the national Poison Control Center hotline at 800-222-1222.

Monitoring

Aside from generally monitoring your pet after application, no specific monitoring is required for this medication. However, most veterinarians routinely screen for parasites during annual exams.

Call Your Vet If:

• Severe side effects are seen (see above)

• Your pet’s condition worsens or does not improve with treatment

• You see or suspect an overdose

• You have additional questions or concerns about the use of Advantage^®, K9 Advantix^® II, or Advantage Multi^®

Advantage®/K9 Advantix® II/Advantage Multi® Overdose Information

Overdose symptoms will depend on which product was used. General symptoms of an overdose may include

• Diarrhea

• Vomiting

• Decreased appetite

When pets are given this medication orally, the following symptoms may be noted in addition to those listed above

• Tremors

• Lack of coordination

• Drooling

• Vomiting

• Cough

• Fatigue (lethargy)

If you suspect an overdose, used the wrong product on your pet, or accidentally gave this topical product by mouth, immediately contact your veterinarian, seek emergency veterinary care, or call an animal poison control center. Consultation fees often apply.

Pet Poison Helpline (855) 764-7661

ASPCA Animal Poison Control (888) 426-4435

Advantage® II

Advantage^® II is a topical over-the-counter product for the prevention and treatment of all life stages of fleas and lice in canines 7 weeks of age and older and weighing more than 3 pounds. It contains the active ingredients imidacloprid and pyriproxyfen.

Feline Advantage®

Feline Advantage^® II is a topical over-the-counter product for the prevention and treatment of all life stages of fleas in felines 7 weeks of age and older and weighing more than 2 pounds. It contains the active ingredients imidacloprid and pyriproxyfen.

Ferret Advantage®

Ferret Advantage^® II is a topical over-the-counter product for the prevention and treatment of all life stages of fleas and lice in ferrets 10 weeks of age and older and weighing more than 1 pound. It contains the active ingredients imidacloprid and pyriproxyfen.

K9 Advantix® II

K9 Advantix^® II is a topical over-the-counter product for the prevention and treatment of all life stages of fleas and lice in canines 7 weeks of age and older and weighing more than 4 pounds. The addition of the medication permethrin helps repel and kill ticks including Deer, American Dog, Lone Star, and Brown dog ticks. K9 Advantix^® II is also labeled to repel mosquitos and biting flies.

Do NOT use this product on felines. Keep felines away from dogs treated with this product for 24 hours.

Advantage Multi®

Advantage Multi^® is a topical over-the-counter product for the prevention and treatment of all life stages of fleas and lice in canines 7 weeks of age and older and weighing more than 3 pounds. The addition of the medication moxidectin allows this product to prevent heartworm disease and can also treat and control scabies (sarcoptic mange) as well as hookworms, roundworms, and whipworms.

Feline Advantage Multi®

Feline Advantage Multi^® is a topical over-the-counter product for the prevention and treatment of all life stages of fleas and lice in felines 9 weeks of age and older and weighing more than 2 pounds. The addition of the medication moxidectin allows this product to treat and control ear mites, hookworms, and roundworms infestations, while also preventing heartworm disease.

Feline Advantage Multi^® is also approved for use in ferrets weighing 2-4.4 pounds. The added benefit of utilizing this product in ferrets is to prevent heartworm disease along with the treatment and prevention of flea infestations.

Advantage®/K9 Advantix® II/Advantage Multi® Storage

All Advantage^®, K9 Advantix^® II, and Advantage Multi^® products should be stored at controlled temperatures between 39-77° F. Protect from freezing.

Keep the medication in the provided blister packs until ready to use in order to protect from moisture and light. 

Keep out of reach of children and pets.