Doxycycline has been found clinically effective in the treatment of a variety of infections caused by susceptible strains of Gram-positive and Gram-negative bacteria and certain other micro- organisms. Information and fact sheets for patients and professionals. Find out side effects, medicine names, dose and uses. Infections that are caused by bacteria are treated with antibiotics. There are several different types of antibiotic available and your doctor needs to take into account various different factors.