A respiratory tract infection (RTI) is an infection of the airways and lungs. It can be caused by a variety of viruses, bacteria, and other microorganisms. Common symptoms of an RTI include coughing, sore throat, runny nose, and fever. In some cases, a person may also experience chest pain, shortness of breath, and difficulty breathing. Treatment for an RTI typically involves rest, fluids, and over-the-counter medications. In more severe cases, antibiotics may be prescribed.