Acute pharyngitis is an acute infectious inflammation of the pharyngeal mucosa, submucosal tissue, and local lymphatic tissue. Acute pharyngitis can occur independently or as part of an upper respiratory tract infection. In its early stages, acute pharyngitis is primarily a viral infection, or a mixed infection of viruses and bacteria. In the later stages of acute pharyngitis, bacterial infection often occurs secondarily. Acute pharyngitis is contagious and tends to occur mainly in winter or spring. The contagion is not by reverse transmission but is generally infectious. Wearing masks or avoiding close contact can generally prevent it, and special isolation measures are usually unnecessary for prevention.