Doxycycline, available under brand names Vibramycin, Contimycin, Nordox and others. It is a broad-spectrum tetracycline-class antibiotic that is used to treat bacterial and parasitic diseases. Bacterial pneumonia, acne, chlamydia infections, Lyme disease, cholera, typhus, and syphilis are all treated with it. It's also used in conjunction with quinine to prevent malaria.