Lufenuron is a veterinary insecticide that acts by inhibiting chitin synthesis, polymerization and deposition in fleas. After biting a lufenuron-treated cat, the female flea ingests a blood meal containing lufenuron which is subsequently deposited in her eggs. Lufenuron prevents flea eggs from hatching and developing into adults and thus controls flea populations by breaking the life cycle. Lufenuron does not kill adult fleas. Lufenuron is used as an ingredient in Sentinel®Flavor Tabs® drug which is indicated for use in dogs and puppies for the prevention of heartworm disease caused by Dirofilaria immitis; for prevention and control of flea populations, control of adult Ancylostoma caninum (hookworm), and removal and control of adult Toxocara canis, Toxascaris leonina (roundworm), and Trichuris vulpis (whipworm) infections. Concurrent use of insecticides may be necessary for adequate control of adult fleas. The concurrent use of flavored milbemycin oxime and lufenuron tablets is indicated to kill adult fleas and prevent flea eggs from hatching. Adverse effects reported in dogs and cats include vomiting, diarrhea, difficulty breathing, rash, itching, and reddened skin. After receiving the injectable product, a small bump at the injection site has been noticed. A few weeks may be required for this to dissipate.