Tetracycline is used to treat infections caused by bacteria including pneumonia and other respiratory tract infections; ; certain infections of skin, eye, lymphatic, intestinal, genital and urinary systems; and certain other infections that are spread by ticks, lice, mites, and infected animals. It is also used along with other medications to treat acne. Tetracycline is also used to treat plague and tuleramia (serious infections that may be spread on purpose as part of a bioterror attack). It can also be used in patients who cannot be treated with penicillin to treat certain types of food poisoning, and anthrax (a serious infection that may be spread on purpose as part of a bioterror attack). Tetracycline is in a class of medications called tetracycline antibiotics. It works by preventing the growth and spread of bacteria. Antibiotics such as tetracycline will not work for colds, flu, or other viral infections. Using antibiotics when they are not needed increases your risk of getting an infection later that resists antibiotic treatment.