Respiratory tract infections, including the common cold and acute sinusitis, affect millions of individuals every year. Colds are caused by viruses, are easily spread from person to person, and are usually short-lived. Sinusitis (infection of the paranasal sinuses) usually occurs as a result of a cold but also can result from swelling of the nasal passages, obstruction from a medical device or a nasal deformity, or as part of a general infectious process in the body. Acute sinusitis may be caused by viruses, bacteria, or, rarely, a fungus infection. Antibiotics may be used to treat bacterial sinusitis. It is important to understand that antibiotics do not help a cold or viral sinusitis. Using antibiotics improperly (such as for a viral infection) can cause resistant bacteria (that cannot be killed by the usual antibiotics) to form, leading to antibiotic-resistant infections. The May 6, 2009, issue of JAMA includes an article about acute rhinosinusitis (infection of the nose and sinuses). This Patient Page is based on one published in the December 5, 2007, issue of JAMA.