Doxycycline is a broad-spectrum tetracycline-class antibiotic used in the treatment of infections caused by bacteria and certain parasites.[1] It is used to treat bacterial pneumonia, acne, chlamydia infections, Lyme disease, cholera, typhus, and syphilis.[1] It is also used to prevent malaria and in combination with quinine, to treat malaria.[1] Doxycycline may be taken by mouth or by injection into a vein.[1]