What causes chronic sinusitis?

What causes chronic sinusitis?

Chronic sinusitis can be caused by several factors. These include:

• Blocked airways from asthma or allergies or from conditions such as cystic fibrosis.
• Infections, which can be bacterial, viral or fungal.
• Abnormal nose structures, such as a deviated septum (the line of cartilage and bone down the middle of the nose is crooked or off to the side).
• Polyps (growths).
• A weak immune system.