Rid your pet and home of fleas for good.

Fleas are the most common external parasite found on pets, and can irritate your pet with constant itching and scratching, hair loss, or flea allergy dermatitis.

Activyl® Topical for Dogs and Cats stops fleas from biting to give your pet quick relief, and breaks the flea life cycle to prevent new fleas from developing. Activyl can be purchased at your veterinary clinic, online or at select retailers near you, to ensure your furry family member gets the best care.

Learn more about Activyl® Protector Band for Dogs to treat both fleas and ticks.

Find out how Activyl® Topical for Dogs & Cats is tough on fleas.

Activyl Topical for Dogs and Cats are topical products that use 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 on the skin and coat. Fleas don’t have to bite to take up Activyl, 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.3,4

Activyl Eliminates over 99% of Fleas6

How Activyl Topical for Dogs & Cats Works3

Applying Activyl® is Easy!

4 Steps to Applying Activyl® Topical for Dogs & Cats

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® Topical Application Chart for Dogs & 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® Topical

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 Shampooing3

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. Frontline® is a registered trademark of Merial.
  6. Dryden MW, et al. Parasites & Vectors. 2013;6:366.