In sinusitis, the membrane that lines the sinuses becomes inflamed. It may be accompanied by inflammation of the nasal lining (rhinitis), in which case the condition is known as rhinosinusitis.
The inflammation may be acute (developing and clearing up rapidly) or chronic (long term). It is usually caused by a viral infection, such as the common cold. The blockage of the sinuses from a viral infection may lead to a build-up of mucus, which may then become infected with bacteria. Blockage is more likely in people with an abnormality of the nose, such as a deviated nasal septum or nasal polyps.
Sinusitis is also more likely to develop in people with hay fever or another form of allergic rhinitis. Symptoms typically include headache, a feeling of fullness around the sinuses, pain in the face that worsens when bending forward, a stuffy or runny nose, and sometimes fever.
Sinusitis usually clears up without treatment, although medication may relieve symptoms. Surgery may be recommended for persistent sinusitis.