What is a vasoconstricting agent?

A vasoconstrictor makes a blood vessel constrict or get smaller by stimulating smooth muscle contraction in the vessel walls. An example is a decongestant nasal spray that vasoconstricts to reduce swelling and mucus production in the nasal membranes to relieve congestion and runny nose. Vasoconstrictors are typically used in medicine to raise blood pressure, reduce swelling, and prevent or slow bleeding.