Xylometazoline Hydrochloride is a drug that works by narrowing blood vessels in the nose, which helps reduce nasal congestion, making Xylomet Plus easier to breathe. Sodium Cromoglicate works locally on the nasal lining to prevent the release of chemicals like histamine that cause allergic reactions. Xylomet Plus does not stop the allergic reaction from happening but reduces the symptoms by stopping these chemicals from being released. Xylomet Plus also helps reduce delayed allergic reactions, though to a lesser extent.