Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Impotence (Erectile Dysfunction)

What Is It?

Impotence means that a man's penis doesn't get hard enough to have sexual intercourse. The man cannot get or maintain an erection. The medical term is erectile dysfunction. This condition affects approximately 30 million men in the United States. Erectile dysfunction is not the same as premature ejaculation, which is ejaculating within 1 minute after initiation of intercourse.

The major causes of erectile dysfunction include:

• Vascular (blood vessel) disease — Erections happen when blood collects in the shaft of the penis. Vascular disease can limit the amount of blood flowing to the penis or the amount staying in the penis. Both can result in problems with erections. Blood vessels can be damaged by hardening of the arteries (atherosclerosis) or trauma. Vascular disease is believed to be the most common medical cause of impotence.

• Nerve damage (neuropathy) — Nerves must be working normally for a man to get and keep an erection. Nerves can be damaged by diabetes, multiple sclerosis, prostate surgery or damage to the spinal cord.

• Psychological factors — Psychological issues such as depression, anxiety, guilt or fear can sometimes cause sexual problems. At one time, these factors were thought to be the major cause of impotence. Doctors now know that physical factors cause impotence in most men with the problem. However, embarrassment or "performance anxiety" can make a physical problem worse. Impotence caused only by psychological causes is found most commonly in young men.

• Medications — Many medications cause problems with sexual function, including drugs for high blood pressure, depression, heart disease and prostate cancer.

• Hormonal problems — Abnormal levels of certain hormones, such as testosterone, thyroid hormone and a pituitary hormone known as prolactin, can interfere with erections and sex drive (libido). This is an uncommon cause of impotence.