It can be due to allergic nasal polyps or tumors, allergic reactions, deviated nasal septum, trauma to the face, respiratory tract infections,
allergies such as
hay fever, immune system cells or cystic fibrosis.
It is important to find out the cause of chronic sinusitis as then specific treatment can be started. Treatment varies from saline and steroid nasal sprays to decongestants and antibiotics. Some resistant cases may need surgery. As for now, inhale plenty of steam.