Sinusitis is an inflammation or swelling of the tissue lining the sinuses. Sinuses are hollow spaces within the bones between your eyes, behind your cheekbones, and in your forehead. They make mucus, which keeps the inside of your nose moist. That, in turn, helps protect against dust, allergens, and pollutants.
Healthy sinuses are filled with air. But when they become blocked and filled with fluid, germs can grow and cause an infection. Sinus symptoms lasting for more than one to two weeks may be more than just a cold.
Conditions that can cause sinusitis include:
- Allergic rhinitis, which is swelling of the lining of the nose cause by allergens
- The Common cold
- Small growths in the lining of the nose called nasal polyps
- A deviated septum, which is a shift in the nasal cavity