Which of the following is a mechanism of action attributed to ephedrine when used as a decongestant?

Ephedrine is primarily known for its action as a sympathomimetic agent, which means it stimulates the sympathetic nervous system. When used as a decongestant, its mechanism of action involves vasoconstriction of blood vessels. This vasoconstriction occurs due to ephedrine's ability to activate alpha-adrenergic receptors in the nasal mucosa, leading to decreased blood flow to the area and resulting in reduced swelling and congestion.

This effectiveness makes it a popular choice for alleviating nasal congestion caused by colds or allergies. The vasoconstriction reduces the volume of blood in the dilated vessels of the nasal passages, contributing to a decrease in mucosal edema and increasing airflow through the nasal passages. The importance of this mechanism is central to the therapeutic use of ephedrine in treating congestion.