Pneumonia is an acute infection of the lung that is often treated with antibiotics. Most patients with pneumonia have symptoms such as shortness of breath, fever, or chest pain. Most get better once treatment begins, but some patients develop serious complications and some die of the infection. Factors that increase the chance of dying of pneumonia include older age, living in a nursing home, having other illnesses (especially cancer), and having certain abnormal physical examination or test results. Experts agree that patients at high risk for dying of pneumonia should be hospitalized for observation and treatment. Patients at low risk for dying may need less close observation and may be able to take antibiotics at home.