Tetracycline is one of the antibiotics. It kills infectual bacteria, which in the body by stopping the growth and evolution of bacteria. The main target of Sumycin is to fight different kinds of infections. They are acne, infections of urinary tract, chlamydia, gonorrhea, and others. Tetracycline Prednison may also be useful for other health problems, which are not described here. If you have an allergy to Sumycin or to some components it consists of don't use it. If you have an allergy on some drugs related to Sumycin you should also avoid using of it. They are minocycline, demeclocycline and doxycycline. It's strongly reccomended to not use this medicine in the case of pregnancy. It can harm your unborn baby. You need to make some tests if the aim of your using of Sumycin is gonorrhea. You should also ask your doctor if this medicine could be compound with other drugs you are taking. You should have consultancy with your doctor before using Tetracycline to prevent negative effects.