Nasal irrigation physically removes secretions, allergens, and bacteria that have accumulated on the mucosa and supports the function of the mucosal cilia. How to do it: prepare saline (bought at a pharmacy or made with 1 L of boiled water plus 9 g of salt) at about body temperature (around 37 degrees Celsius). Tilt your head 45 degrees and pour into one nostril so that it comes out the other side. Use 150 to 250 mL per session, once or twice a day. Cautions: do not use tap water (which contains chlorine) directly, and wash and dry the irrigation container daily to prevent bacterial growth. Irrigating too often (more than three times a day) can wash away even the protective mucus and actually cause dryness.