Sinuses are small pockets behind your nose, cheekbones, forehead, and middle of your eyes. Their job is to protect your body from germs. By secreting mucus (a thin layer of liquid), they trap and move germs out of your body. That’s what happens when your nose runs.
Healthy sinuses contain air. However, they can become blocked and filled with mucus when you have a cold or allergies, for instance.
This can cause germs to grow in the mucus which leads to an infection of the sinuses. This is when the symptoms of sinusitis show up.
Other things that can cause sinusitis are:
- Allergic rhinitis—the swelling of your nasal lining which can be the effect of allergens
- A deviated septum—a shift of your nasal cavity
- Nasal polyps—small growths in the lining of your nose
- Asthma Pollutants and chemical irritants