The cephalosporins have been employed in the treatment of infections since the 1960s. They have grown in popularity and are the most commonly used antibiotics today. Due to this, the number of bacteria resistant to this group is rising. Their structure and function are similar to penicillin and they are considered to be beta-lactam antibiotics. Cephalosporins are bactericidal and possess low toxicity. They have been divided into four generations and as progression is made from the first generation to the fourth generation: activity against gram-negative bacteria increases, ability to penetrate cerebrospinal fluid increases, cost increases, and there is greater resistance to beta-lactamases. The cephalosporins are well-distributed to most body tissues and fluids and are eliminated by the kidney.