Sinusitis is an inflammation of the mucous membrane of the paranasal sinuses. Synonyms: maxillary sinusitis, ethmoiditis, frontal sinusitis, sphenoiditis, hemisinusitis, pansinusitis. The clinical course and symptoms of acute sinusitis are very similar. Usually, against the background of recovery from ARVI and flu, a temperature reaction appears again, weakness, health deteriorates, symptoms of intoxication increase, reactive edema of the eyes and cheeks, profuse purulent discharge from the nose, pain in the sinus area appears (especially in young children).