Vasoconstriction is the narrowing (constriction) of blood vessels by muscles in their walls. When blood vessels constrict, the flow of blood is restricted or slowed.

Vasoconstriction may be slight or severe. It may result from disease, medication, or psychological conditions. Medications that cause vasoconstriction include:

• Decongestants, including pseudoephedrine
• Cough and cold combinations
• Caffeine

Medications may be used to increase or reduce vasoconstriction in very ill patients.