Vicks Sinex Micromist is a decongestant nasal spray that provides a relief from a blocked nose due to common colds and hayfever with a refreshing scent of Menthol and Eucalyptus. Metered spray bottle delivers an accurate therapeutic dose in an ultra fine mist The effect of the spray starts within minutes and last for up to 8 hours. The active substance is oxymetazoline hydrochloride.