Doxycycline is an antibiotic that belongs to the tetracycline class of medications. It is commonly used to treat a variety of bacterial infections, including respiratory tract infections, urinary tract infections, and certain skin conditions. Doxycycline works by inhibiting the growth of bacteria, making it effective against both gram-positive and gram-negative bacteria. In addition to treating infections, doxycycline is also used for other purposes, such as preventing malaria and treating acne. It is usually taken orally in the form of a tablet or capsule, and it is important to follow a healthcare provider's instructions regarding dosage and duration of treatment to ensure effectiveness and reduce the risk of resistance.