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decongestant de·con·ges·tant (dē'kən-jěs'tənt)
A medication or treatment that breaks up congestion, as that of the sinuses, by reducing swelling. adj.
Capable of relieving congestion.
any drug used to relieve swelling of the nasal mucosa accompanying such conditions as the common cold and hay fever. When administered in nasal sprays or drops or in devices for inhalation, decongestants shrink the mucous membranes lining the nasal cavity by contracting the muscles of blood vessel walls, thus reducing blood flow to the inflamed areas. The constricting action chiefly affects the smallest arteries, the arterioles, although capillaries, veins, and larger arteries respond to some degree