Phentolamine mesylate is a short-acting non-selective alpha-blocker that simultaneously dilates arteries and veins, reduces peripheral resistance and pulmonary artery pressure, and has an excitatory effect on the heart, causing increased heart rate, increased cardiac output, and increased myocardial oxygen consumption. Therefore, it is prohibited in patients with ischemic cardiomyopathy and myocardial infarction. The peak blood concentration is reached in 2 minutes of intravenous injection and lasts for 15-30 minutes. It is commonly used clinically in hypertensive emergencies, especially as a drug of choice in pheochromocytoma episodes, colistin withdrawal syndrome; it is also used in peripheral vascular disease, anti-shock therapy. Its main adverse effects include postural hypotension, reflex tachycardia, angina pectoris, as well as vertigo, headache, drowsiness, palpitations, nausea, weakness, constipation, rash, and occasionally peripheral tissue edema, blurred vision, and other adverse effects.