Tetracycline antibiotics are used to treat bacterial infections such as acne, respiratory tract infections, and urinary tract infections. They also have other uses, including treating certain sexually transmitted infections and Lyme disease. These medications work by inhibiting the growth of bacteria, helping your body to fight off the infection. Tetracycline antibiotics come in different forms, including oral pills and injectable solutions. Examples include doxycycline hyclate (Vibramycin, Acticlate, Morgidox), doxycycline monohydrate (Mondoxyne NL, Monodox, Oracea), and doxycycline delayed-release (Oracea).