Nasal irrigation, or nasal douche, is a therapy that involves flushing the nasal passages with a saline solution or clean water. This treatment is used to cleanse the nasal passages, remove secretions, and clear any obstructions or allergens present. Nasal irrigation is particularly useful for treating respiratory disorders such as allergic rhinitis, sinusitis, nasal congestion, and improving breathing. This therapy can be performed using a special syringe or a specific device.