Sinuses are air-filled spaces behind the bones of the upper face: between the eyes and behind the forehead, nose and cheeks. The lining of the sinuses are made up of cells with tiny hairs on their surfaces called cilia. Other cells in the lining produce mucus. The mucus traps germs and pollutants and the cilia push the mucus out through narrow sinus openings into the nose.
When the sinuses become inflamed or infected, the mucus thickens and clogs the openings to one or more sinuses. Fluid builds up inside the sinuses causing increased pressure. Also bacteria can become trapped, multiply and infect the lining. This is sinusitis.
sinusitis is can be chronic (long-lasting or frequently returning) or acute. Acute sinusitis lasts three weeks or less and the person should have no more than three episodes per year. Acute sinusitis is extremely common. It usually is caused by an upper respiratory viral infection.
The inflammation and swelling of the lining of the sinuses can be triggered by:
Common symptoms of acute sinusitis include nasal congestion, thick green nasal discharge, fever, headache, tiredness and facial pain. Some symptoms depend on which sinus is inflamed. For example:
A sinus infection can be difficult to diagnose in the early stages because it can mimic a common cold. Both can cause nasal congestion and fatigue. However, a common cold usually will improve in five to seven days, while an untreated sinus infection can last three weeks or longer. Sinus infections also are more likely to cause a green nasal discharge, fever and facial pain.