Insufficient blood supply to the penis mainly refers to insufficient blood supply to the corpus cavernosum of the penis, which is mainly composed of the corpus cavernosum. The corpus cavernosum of the penis will have an erection when the blood supply is sufficient, and if the blood supply is insufficient, it will make the penis not hard or unable to have an erection during sexual intercourse. There are many vasoactive drugs that can improve the blood circulation in the cavernous body of the penis and increase the blood supply to the cavernous body, thus increasing the hardness and duration of erection during sexual intercourse. Commonly used clinical drugs, such as sildenafil and tadalafil, can increase the diameter of the penile arteries and cause them to dilate, thus increasing the blood supply to the corpus cavernosum. In addition, other topical vasoactive drugs, such as prostaglandin E1, or prostilbestrol, can improve the blood supply to the penile corpus cavernosum, thus promoting erection.