Advantage II for Cats

Written By Kim Rain
Published: 07/30/2021Updated: 10/28/2021
Advantage II for Cats

Advantage II for Cats is a topical insecticide used to kill fleas, flea eggs and larvae that are present on cats, and prevent an infestation. This fast-acting medication contains two active ingredients, imidacloprid and pyriproxyfen, which effectively kills adult fleas within 12 hours of application, and actively inhibits younger fleas from maturing. Once applied, Advantage II continues to kill and repel fleas for a month. While used effectively for flea control on pet cats, Advantage II can also be used to help treat flea allergy dermatitis in cats by preventing fleas from biting and triggering symptoms of this condition.


Advantage II for Cats is available in 3 formulations, one for kittens that are 2 to 5 lbs., one for small cats weighing 5 to 9 lbs., and another for large cats that weigh over 9 lbs. The kitten formulation is available in a 2-dose packet for 2 months at $26.98. Both the small and large cat formulations can be purchased in 1-dose to 12-dose packets that range from $15 to $116. All kinds of Advantage II are available for purchase through your veterinarian, in retail stores and online.


Advantage II for Cats is used only on kittens and cats that are 8 weeks of age and older, and weigh no less than 2 lbs. When using as a general flea control, this product is applied once a month. If using to control an existing severe flea infestation, your veterinarian may prescribe this treatment several times within the same month. Dosing is as follows:

  • For flea prevention: Apply 1 tube of appropriate formulation to cat, once monthly.
  • For treatment of flea infestation: Apply 1 tube of appropriate formulation to cat once. Re-apply within the same month as directed by your veterinarian to eliminate all fleas.

Dosage instructions

Before applying, be sure your cat is at least 8 weeks of age and weighs 2 lbs. Choose the appropriate formulation based on your cat’s weight, and never use any formulation that is made for dogs or another animal on your cat.

To apply, open one tube of Advantage II for Cats by holding upright and twisting the cap until it detaches. Move the hair at the base of your cat’s skull on their neck until you see skin, then squeeze the entire tube of liquid onto the skin. Put hair back into place to cover liquid. When applying, be careful to not get product into your cat’s eyes or mouth. If liquid runs off the application spot, try to use applicator to massage into skin and under the fur so that your cat cannot reach it to lick it off.

Advantage II begins to work within 12 hours, but it may take an entire 30-day cycle to treat an existing flea infestation. Be sure to also treat areas that fleas may be living, such as pet beds, carpets and rugs, and dose every animal in the household at the same time with an appropriate formulation to prevent re-infestation.  

This medication can be toxic to humans if ingested or gets in the eyes, so be sure to wash your hands thoroughly after application, and let product dry on cat before touching them in the application area.


Advantage II for Cats is formulated with 9.10% imidacloprid and 0.46% pyriproxyfen, and has proven to be quite effective in treating and preventing flea infestations. Imidacloprid attacks fleas by targeting their nervous system which paralyzes them, then kills them. Pyriproxyfen is an insect growth regulator that works by preventing immature fleas from evolving into adults. The most common flea that attacks cats and dogs is the cat flea, or Ctenocephalides felis.

Several studies have discovered that imidacloprid kills 95% of adult fleas and flea larvae up to 61 days after treatment, as well as prevents flea eggs from hatching for up to 7 weeks. Pyriproxyfen has a lower efficacy of flea fatalities at 49%, but 100% of the eggs that had been exposed to it for only 3 days failed to hatch. After adult fleas were exposed for 3 days, 100% of the next 14 days of eggs also failed to hatch. In fact, a 2-hour exposure also resulted in 100% inhibition. When these two insecticides work together, they lessen the time it takes to kill adult fleas and prevent new fleas from developing or hatching.

Side Effects

When used as directed, there are rarely side effects reported with Advantage II for Cats. Signs of an adverse reaction can include:

  • Reddened skin at application site
  • Scratching
  • Drooling
  • Vomiting
  • Diarrhea
  • Lethargy
  • Irritability
  • Unusual breathing
  • Loss of muscle control

If your cat licks the solution, either directly or off their paw after scratching, the bitter taste will often cause excessive drooling, and may cause vomiting. If this occurs, offer your cat some wet food or tuna, and water. The product should only cause mild gastrointestinal discomfort and should pass. Once dried, the solution should not cause the same issues. If you cannot prevent your cat from consuming the solution, you can bathe them in dish soap up to three times to remove it.

If side effects worsen, continue or become severe, speak with your veterinarian right away.


Be sure to never use Advantage II for Cats on kittens and cats under 8 weeks of age or weighing less than 2 lbs. Do not use more than 1 tube each treatment on a cat, even if they are very large. Always talk with your veterinarian if your cat is pregnant or lactating before using this product.

When treating a flea infestation, always treat all animals and areas of infestation in the household at the same time.

Some cats can experience or develop a sensitivity to any pesticide, so be sure to discuss any adverse reactions with your veterinarian.

Drug Interactions

While there are no known drug interactions between Advantage II and any other specific drugs, you should talk with your veterinarian if your cat is on any medications before using this product.

Allergic Reactions and Sensitivity

Although rare, some cats may be allergic or sensitive to the ingredients in Advantage II for Cats or other flea medications. Many of the symptoms of an allergy or sensitivity are similar to the medication’s side effects, such as drooling, vomiting, diarrhea, itching and skin irritation, and lethargy, but it can also cause difficulty breathing, loss of appetite and seizures. If you suspect your cat is experiencing an allergy to this product, contact your veterinarian.

Frequently Asked Questions

Does Advantage II require a prescription?

Advantage II does not require a prescription from your veterinarian, and can be purchased from your vet, from retail stores, and online.

Does Advantage II expire?

Since the EPA does not require expiration dates on packaging for Advantage II, there is no expiration date listed.

What do I do if I skip a dose?

If you miss a dose of Advantage II, simply apply to your cat when you remember and then start your 30-day clock for the next monthly dose.

How do I store Advantage II?

Store this product in its original packaging in a cool, dry place. Keep out of reach of children, and do not freeze. Once used, throw tubes away. If you need to dispose of liquid, be sure not to pour it down any inside or outside drains.

Can my cat be bathed after applying Advantage II?

After 24 hours from application, Advantage II for Cats is waterproof and should not come off of your cat during bathing, just be sure the solution has dried first. However, it is recommended to bathe your cat before applying the solution as each bathing session can reduce its effectiveness.

Can I use Advantage II for Cats on dogs?

You should never use Advantage II for Cats on dogs, or a dog formulated product on cats as they contain different amounts of each active ingredient that is specific to breed and weight. Always follow the label directions for any flea product.


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