Demeclocycline is used to treat infections caused by bacteria includingpneumonia and other respiratory tract infections;; certain infections of the 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. Demeclocycline is also used to treat plague and tularemia (serious infections that may be spread on purpose as part of a bioterror attack). Demeclocycline can also be used in patients who cannot be treated with penicillin to treat certain types of food poisoning and anthrax (a very serious infection that may be spread on purpose as part of a bioterror attack), Demeclocycline is in a class of medications called tetracycline antibiotics.