Cefalexin also known as cephalexin and sold under the brand names Keflex and Ceporex is a type of drug called an antibiotic. It is a type of antibiotic called a cephalosporin. Cefalexin can treat some bacterial infections in areas including the ear, bone, joint, skin, and bladder.  It may also be used for some types of pneumonia and strep throat. Like other antibiotics, cefalexin cannot treat viral infections, such as the flu or common cold.