Nasal spray oil are also available. There is however no trial-verified evidence that they have a measurable effect on symptoms. Decongestant nasal sprays are available over-the-counter in many countries. They work to very quickly open up nasal passages by constricting blood vessels in the lining of the nose. Prolonged use of these types of sprays can damage the delicate mucous membranes in the nose. This causes increased inflammation, an effect known as rhinitis medicamentosa or the rebound effect. Decongestant nasal sprays are advised for short-term use only, preferably 5 to 7 days at maximum. Some doctors advise to use them 3 days
Nasal irrigation cases of fatal naegleriasis have occurred due to nasal insufflation of the amoeba "Naegleria fowleri" from untreated tap water. Flushing the nasal cavity can soothe inflamed tissue and remove irritants like allergens; it may help clear mucus. The water should not be tap water, which may contain small amounts of bacteria that are safe to drink but may be dangerous in the nose. The water should be sterile or filtered for micro-organisms; if tap water is used it should be boiled. Saline solution is also sometimes used. A number of other compounds may be included in irrigation fluids such as