Sinus Infection Overview. Sinus infection, or sinusitis, is an inflammation of the sinuses and nasal passages. A sinus infection can cause a headache or pressure in the eyes, nose, cheek area, or on one side of the head. A person with a sinus infection may also have a cough, sore throat, fever, bad breath, and nasal congestion with thick nasal secretions. Sinusitis is categorized as acute (sudden onset) or chronic (long term, the most common type). Sinusitis is very common. Here is an overview of the anatomy of the sinuses (also called paranasal sinuses). The human skull contains four major pairs of hollow air-filled cavities called sinuses. These are connected to the space between the nostrils and the nasal passage (behind your nose).