Pharyngitis, otherwise known as a sore throat, is inflammation of the pharynx, the portion of the throat that lies just beyond the back of the roof of the mouth and stretches to the Adam's apple (larynx). It usually occurs when viruses (or sometimes, bacteria) from a cold, flu, or sinus infection involve the throat. Pharyngitis is very common but rarely serious. Most cases clear up on their own after three to 10 days and require no therapy other than pain relievers to ease discomfort. Some cases will require antibiotic therapy to treat a bacterial cause.