Stop the Pests, Not Your Pets

Rid your pet and home of fleas for good.

Fleas are the most common external parasite found on cats and dogs, and can irritate your pet with constant itching and scratching, hair loss, or flea allergy dermatitis.6 A small flea problem left untreated can easily become an issue for the entire home.

Activyl is efficient for your pet and can be used safely. It stops fleas from biting to give your pet quick relief, and breaks the flea life cycle to prevent new fleas from developing. It is quick-drying, fragrance-free and waterproof even after bathing. Ask your veterinarian for more information.

If your dog has fleas and ticks, learn more about Activyl Tick Plus for Dogs.

Your Pet is Itching for Greater Protection

Activyl for Dogs and Activyl for Cats are spot-on products that contain indoxacarb and a mode of action that uses enzymes inside the flea to activate serious flea-killing power. They are applied to a small area of skin but soon spread. Fleas don’t have to bite for Activyl to work; simply coming into contact with the skin is enough.

By stopping flea eggs and larvae, in addition to killing adult fleas, Activyl breaks the life cycle. This is effective at both killing and preventing infestations in the home.3,4

Activyl Outperforms Frontline® Plus2

How Activyl Works3

Applying Activyl Is Spot-on!

4 Steps to Applying Activyl

Choose a room in your house where your pet feels comfortable and relaxed, with a surface that's easy to clean in case of spillage.

Activyl Application Size Chart for Dogs and Cats


Place the product at the base of the skull to help prevent your cat from licking it. Squeeze the applicator firmly, applying the entire contents directly onto the skin.

Small Dogs

Place the applicator tip against the skin between the shoulder blades. Squeeze the applicator firmly, applying the entire contents directly onto the skin.

Activyl® Spot-On

Select the species and weight to view which product is best for your pet.

Cat | 2-9 lbs

Cat > 9 lbs

Dog | 4-14 lbs

Dog | 14-22 lbs

Dog | 22-44 lbs

Dog | 44-88 lbs

Dog | 88-132 lbs

Safety and Tips

Container Handling Instructions

Do not reuse the Activyl container. Place in trash or offer for recycling if available. If partly filled: call your local solid waste agency for disposal instructions. Never place unused products down any indoor or outdoor drain.

Activyl Is Waterproof and Resists Shampooing

Activyl has been tested to make sure it is not easily rinsed or washed off. However, Activyl must first be allowed to spread and dry on the skin. According to veterinary industry standards, you should not wash your pets or allow them to swim for 24 to 48 hours after application.

  1. Blagburn BL, Dryden MW. Biology, treatment, and control of flea and tick infestations. Vet Clin N Am Small Anim Pract. 2009;39(6):1173-1200.
  2. Dryden M, Rust M. The cat flea: biology, ecology and control. Vet Parasitol. 1994;52:1-19.
  3. Data on file, Merck Animal Health
  4. Guerino F, Qureshi T, Hair J, Young D, Fiourie J. Indoxacarb Kills Developing Stages of Fleas in the Environment of Treated Cats. Presented at the WSAVA/FECAVA/BSAVA World Congress. 12-15 April 2012. Birmingham, UK.
  5. Fisara P, Sargent R, Flochlay-Sigognault A, Frenais R, Guerino F. Efficacy of indoxacarb spot-on in resolving clinical signs of flea allergy dermatitis in dogs, cats and other field conditions. Presented at the BSAVA/WSAVA/FECAVA World Congress, 12-15 April, 2012, Birmingham, UK.