Description Cephalexin is an antibiotic, used to treat infections. Drug Uses Cephalexin is used to treat infections, caused by bacteria that are susceptible to the effects of cephalexin. Common infections that are treated with cephalexin include infections of the middle ear, tonsils, throat, larynx (laryngitis), bronchi (bronchitis) and pneumonia. It also is used for treating urinary tract, skin and bone infections.