Vicks sinex micromist nasal spray is a nasal spray used for localised relief of the symptoms of a blocked nose in association with a cold hayfever or sinusitis inflammation of the passages leading to the nose the effect of the spray starts after several minutes and lasts for 6 8 hours the active substance is oxymetazoline hydrochlorideas an alternative doctors can also prescribe medication that can assist with flu please visit our online doctor service to proceed with an influenza cons