Mar Vista Animal Medical Center

3850 Grand View Blvd.
Los Angeles, CA 90066




(for veterinary information only)




45 mg, 90 mg, 204.9 mg, & 409.8 mg
and is included in



In older times, flea control for pets was all about shampoos, sprays, foggers, flea collars and powders. The U.S. market had been long in search of a flea product that was safe, convenient, and effective and many companies were racing to bring out their new product first. Ciba Animal Health won this battle in 1995 with the approval of lufenuron for use in U.S. pets. The introduction of lufenuron marked what is called the "revolution" in flea control where products shifted towards monthly oral and topical products and away from the labor-intensive materials of the past. Lufenuron does not kills fleas but it is highly effective at ending flea reproduction. This means that it is best used in combination with other products. It is presently available as an over-the-counter oral medication or as an "every six month" injectable for cats.



Insects are protected in the world by a hard exoskeleton made of a material called chitin. Lufenuron inhibits the production of chitin in insects.

By the time a flea has reached adulthood and is taking blood meals from a pet, it has made all the chitin it needs and is not directly affected by the lufenuron it is drinking in the pet's blood. The female flea, however, is largely drinking blood to support egg-laying (up to 40 eggs daily) and the larvae developing inside these eggs must make chitin in order to chip their way out of the egg. If the mother flea has passed along a healthy dose of lufenuron to her eggs, they will not be able to hatch.

Adult fleas feeding on a pet will be continually producing the black specks of digested blood called flea dirt. This material is highly nutritious for larvae developing in the environment but if this flea dirt is packed with lufenuron, the larvae will not be able to grow normal exoskeletons and they will die.

The injectable formula for cats was designed as an alternative to the relatively unpopular and now discontinued oral liquid. Like the oral product, injectable lufenuron is stored in body fat. One injection is effective for 6 months.


Electron Micrograph of a fleaElectron Micrograph of a flea
(Photo Credit: CDC Public Health Image Library)

Fleas are not the only organisms to contain chitin. Apparently some fungi also are affected by lufenuron. An "anti-ringworm" dose, which is much higher than the flea preventive dose, has been published to aid in the treatment of dermatophytosis (more commonly known as "ringworm.") The efficacy of lufenuron for fungal diseases has not panned out, however, and this unapproved use of lufenuron should be considered as only an adjunct to more traditional therapies, if at all. Lufenuron should not be used as a sole therapy for ringworm. As for other fungi, lufenuron use seems cost prohibitive but may be of benefit as adjunctive therapy.


Oral lufenuron must be given on a full stomach in order to be properly absorbed into the body.

Since lufenuron works on enzymes systems that are unique to insects, no other side effects have been reported even in animals fed hundreds of times the recommended dose.



Program does not interact with other medications. Program is therefore compatible with all other treatments.

It is important to note that with the advent of popular top-spot and oral treatments for fleas, special attention should be paid to the development of resistance to these products. Experience with other insects tells us that resistance can develop in 12 to 15 generations. In order to preserve these new insecticides, it is important to consider what is called integrated pest management. What this means is that insecticides should be rotated or combined with insect development inhibitors such as lufenuron or insect growth regulators like methoprene or pyriproxifen (substances that interfere with the maturation of flea larvae). Adding a second product that breaks the flea life cycle in another stage is very helpful in preventing the development of resistance. Lufenuron may be used in combination with any of the popular effective topicals or oral products to achieve this end.

To see a comparison of popular effective topical flea products click here.



In order for lufenuron to work, fleas must bite the pet, potentially a problem for the flea allergic pet. For pets with flea bite allergy, lufenuron would best be combined with a product that actually kills fleas. There is at present no flea product that can kill fleas before they bite.

Oral lufenuron must be given on a full stomach. Each oral dose lasts 30 days.

Kittens must be at least 6 weeks of age and puppies must be at least 4 weeks of age to begin taking lufenuron. 


Page last updated: 3/20/2019
Page last reviewed: 10/4/2020