Phentolamine Mesylate Tablets is a drug for erectile dysfunction that is effective in getting a sustained erection without sexual stimulation. However, it has more side effects than sildenafil that type of drug, most notably it tends to cause low blood pressure, causing discomfort such as dizziness and headache, and angina in coronary heart patients. Because phentolamine mesylate tablets are alpha adrenergic receptor blockers, mainly by blocking the alpha adrenergic receptors can make the smooth muscle of the penile corpus cavernosum diastolic, the vascular sinuses of the corpus cavernosum open, thus allowing the penis to fill with blood and erection, but at the same time will also act on the blood vessels of the whole body, causing vasodilation and a drop in blood pressure.