Nasal saline irrigation can be especially helpful in people with nasal polyps and chronic sinus infections. This is especially true for those who have had sinus surgery, as the saline can rinse out the sinuses and not just the nasal passages.
Saline rinses help to prevent the crusting of secretions in the nasal passages, which may otherwise block the sinuses from draining. If the sinus drainage sites become blocked, which could also occur with swelling from allergies or irritants, a sinus infection may develop. Saline rinses also serve to reduce tissue swelling in the nasal passages, and improve the clearance of mucus.