Sinusitis is an inflammation of the mucous membrane of the paranasal sinuses. Synonyms: sinusitis, etmoiditis, frontitis, sphenoiditis, hemisinusitis, pansinusitis. The clinical course and symptoms of acute sinusitis are very similar. Usually, on the background of recovery from acute respiratory viral infection and influenza, the temperature response, weakness, the state of health worsens, the symptoms of intoxication appear, the reactive edema of the eyes and cheeks, profuse purulent discharge from the nose, and pain in the sinus area appear (especially in young children).