Your nose has a lot to deal with: pollen in spring, viruses and bacteria in winter. People with an allergy to animal hair or dust can suffer from a blocked nose off and on throughout the year. Nasal spray can provide reliable relief. The little bottle contains a solution of so-called alpha sympathomimetics, substances that cause the blood vessels in the nasal mucosa to constrict, bringing the swelling down and allowing the air to pass through your nose again. The effects of nasal spray last a few hours, enabling you to breathe normally.