Major Uses

Fipronil (a phenylpyrazole antiparasitic agent) and methoprene (an insect growth regulator) work together to kill adult fleas, larval fleas, and flea eggs. The combination product also eliminates ticks of all stages. It kills insects by interfering with their nervous system. Fipronil and methoprene also help control chewing lice and the product is useful in the treatment of sarcoptic mange and cheyletiellosis.

Fipronil and methoprene together form a topical product for cats and dogs that is not absorbed into the body. Proper use helps protect against numerous diseases and infections, including Lyme disease and Rocky Mountain spotted fever. The product's beneficial effects last approximately 30 days, even after multiple baths.

Common Precautions

Fipronil and methoprene may cause skin irritation at the application site. This side effect is temporary. The application site may appear oily or wet for up to 24 hours.

Fipronil and methoprene should only be used on puppies and kittens over 8 weeks of age. The product is not for use on geriatric or debilitated animals. Fipronil and methoprene can cause moderate eye and skin irritation and the product is for external use only.

This flea and tick control product may interact with other drugs or supplements. It is important to disclose all current and recent medications and supplements to a veterinarian before beginning treatment with fipronil and methoprene. Fipronil and methoprene should not be used in animals with a known allergy or hypersensitivity to the drug. Overdose of fipronil and methoprene is not likely, even at up to 5 times the dose. Any known or suspected overdose should be reported to a veterinarian right away.


Fipronil and methoprene should be stored in the original packaging, at room temperature, and out of reach of children and animals. Special disposal procedures are required for partly filled containers. The product is combustible and should not be kept or used near heat sources or open flame.


The combination product of fipronil and methoprene is available as a topical solution at a strength of 9.8% fipronil and 8.8% methoprene.

Dosing of fipronil and methoprene is based on weight and administered once monthly. Dogs weighing up to 22 pounds should be treated with one 0.69 ml pipette. Dogs weighing 23 to 44 pounds require one 1.36 ml pipette, and dogs weighing 45 to 88 pounds need one 2.7 ml pipette. Very large dogs weighing 89 to 132 pounds should be treated with one 4.02 ml pipette. Cats are dosed with one 0.52 ml pipette.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

This product is designed for once monthly application. If a dose is missed, it should be applied as soon as possible. Two doses of this product should not be applied within any 30 day period.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.