Doxycycline is used to treat a variety of infections caused by certain types of bacteria. Doxycycline is also used to treat or prevent anthrax (a serious infection that may be spread on purpose as part of a bioterror attack) in people who may have been exposed to anthrax in the air and to treat plague and tuleramia (serious infections that may be spread on purpose as part of a bioterror attack). It is also used to prevent malaria. Doxycycline is also used along with other medications to treat acne and rosacea (a skin disease that causes redness, flushing, and pimples on the face). Doxycycline (Oracea) is used only to treat pimples and bumps caused by rosacea. Doxycycline is in a class of medications called tetracycline antibiotics. It works to treat infections by preventing the growth and spread of bacteria. It works to treat acne by killing the bacteria that infects pores and decreasing a certain natural oily substance that causes acne. It works to treat rosacea by decreasing the inflammation that causes this condition. Antibiotics such as doxycycline 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.