Doxycycline is a medication (available both orally and in an intravenous form) that, like minocycline, belongs to a class of broad-spectrum antibiotics known as tetracycline antibiotics. Marketed under the brand name Doryx, doxycycline has a wide range of uses in the treatment of bacterial and parasitic infections. Doxycycline is used in the treatment of acne, sexually transmitted infections such as chlamydia identified by STD testing, Lyme disease and pneumonia. Doxycycline is also used in malaria prevention. Doxycycline works by preventing bacteria from making proteins using the 30S ribosomal subunit, thereby preventing reproduction. Doxycycline and alcohol should not be taken together. Doxycycline has historically been used along with azithromycin in the treatment of sexually transmitted diseases.