SINUSITIS - acute or chronic inflammation of the paranasal sinuses. It can be one- or two-sided with the involvement of a sinus or all of the paranasal sinuses on one or both sides (the so-called pansinusitis). Often there is a lesion of the maxillary sinus - antritis , followed by ethmoiditis , frontal sinusitis, and sphenoiditis. Prevention of sinusitis should be aimed at treating the underlying disease (influenza, acute rhinitis , measles , scarlet fever and other infectious diseases, caries and other teeth lesions), elimination of predisposing factors (deviation of the nasal septum, etc.). Hardening plays an important role.