Sinusitis (or rhinosinusitis) isinflammation of the mucous membranes of the sinuses, the cavities located in the forehead (frontal sinuses), above the nose (sphenoidal and ethmoidal sinuses) and on either side of the nose (maxillary sinuses). The sinuses are cavities in the facial bones lined with mucous membrane and communicating with the nasal cavities. Sinusitis most often affects the maxillary sinuses.
Its main cause is viral (during a cold, for example), but it can also be bacterial or caused by an allergic reaction or exposure to irritating fumes (pollution, tobacco, pollen, etc.). Dental abscesses or inflammation can also be the cause.
When you have sinusitis, the mucous membranes lining your sinuses become inflamed, swollen and irritated, which can block the passage of mucus. When the mucus can no longer be transported and eliminated through the nose, it builds up in the sinuses, creating a sensation of painful congestion and allowing bacteria to spread more rapidly.
Sinusitis can be acute, recurrent (more than 3 times a year) or chronic (lasting more than 3 months). Acute sinusitis can last up to 4 weeks.














