Phentolamine mesylate is an alpha-blocker, which can indirectly agonize beta receptors by blocking alpha receptors, rapidly causing peripheral vasodilation, reducing peripheral vascular resistance, increasing peripheral blood volume and improving microcirculation. Initially, it is mainly used for the excitatory effect of the heart, causing increased cardiac contractility, faster heart rate and increased cardiac output, and is used for the treatment of pulmonary edema, acute heart failure, vasospastic diseases, etc. It also has the effect of helping erection by relaxing the smooth muscles of the cavernous body of the penis, allowing more blood to flow into the cavernous body of the penis and stopping the rapid outflow of blood from the cavernous body to make an erection. The effect can last about three hours. Common side effects include nasal congestion, palpitations, flushing, dizziness, chest tightness, and low blood pressure, among other reactions. Phentolamine mesylate is not usually used as the drug of choice in the clinical treatment of erectile dysfunction.