Doxycycline is an antibiotic that is used to treat a wide variety of bacterial infections. It is a member of the tetracycline family of antibiotics, which are used to treat a variety of infections caused by bacteria, such as urinary tract infections, acne, gonorrhea, and chlamydia. Doxycycline is also used to prevent malaria, and is sometimes used to treat anthrax and certain types of infections caused by parasites. Doxycycline is available in both oral and injectable forms, and is generally taken twice a day. The usual dosage is two 100-milligram capsules, taken twice a day, with or without food. It is important to take doxycycline exactly as prescribed by your doctor. Doxycycline works by inhibiting the growth of bacteria by interfering with their ability to produce proteins that are necessary for their survival. It also acts to reduce inflammation, which can help to reduce the symptoms of some bacterial infections.