Sinusitis is caused by one of four main factors: an infection, allergic rhinitis, formation of nasal polyps, or a deviated septum. While sinusitis simply refers to inflammation of the nasal passages, the symptoms and treatments can prove more complex. An acute case of sinusitis (recently occurring) becomes chronic when medical treatments fail to cure the problem after eight weeks.

The symptoms of sinusitis vary depending on whether the condition is acute or chronic. Many of the symptoms for either case are the same, though there are slight variations. With chronic sinusitis, in particular, symptoms last for eight weeks or more and may include facial pain and pressure, nasal congestion, nasal discharge, trouble breathing through the nose, congestion, cough, fever, fatigue, bad breath, headache, ear pain, sore throat, or nausea. If a case of severe sinusitis develops, symptoms such as confusion, double-vision, stiff neck, swollen forehead, and shortness of breath may happen as well.