Blocked nose, nasal congestion and nasal catarrh can be very annoying symptoms of a cold. Try Vicks nasal spray. Vicks Sinex Micromist is a nasal spray used for localised relief of the symptoms of a blocked nose in association with a cold, hay fever 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 hydrochloride.