How do antibiotics work?

Antibiotics either inhibit the growth of bacteria (bacteriostatic) or actually kill the bacteria (bacteriocidal). By stopping the growth of bacteria, it gives the body time to mount an immune response and allows the body to eliminate the bacteria. Drugs that kill the bacteria are the preferred choice when someone has a weakened immune system and whose body cannot destroy the bacteria on its own. Antibiotics are not effective against viruses.