Erectile Dysfunction

Erectile dysfunction (ED) is a medical condition in which a man cannot develop or maintain an erection of the penis.

What Is Erectile Dysfunction?

Erectile dysfunction (ED) is a medical condition that affects men of all races and all regions. The National Institute of Diabetes and Digestive and Kidney Diseases estimated as of 2016 that as many as 30 million men in the United States are affected by ED. Men with ED are unable to achieve and maintain an erection long enough to have sexual intercourse. The condition may have physiologic, psychological, or lifestyle-related causes. Although many causes are treatable and can be remedied with medication, there may be more serious underlying health conditions present. ED can cause a great deal of emotional strain on both the patient and his partner. To understand what causes ED, it is important to know how the penis becomes erect.

Anatomy of an Erection

The shaft of the penis contains several structures that work together to make the penis erect. The corpus cavernosum consists of two long, spongelike structures that run along the length of the penis. They contain erectile tissue, two main arteries, several veins, and nerves. Beneath the corpus cavernosa is the urethra, the tube that carries semen * and urine to the outside of the body through the meatus, the opening in the head at the end of the shaft.

Anatomy of the human male reproductive system.

Anatomy of the human male reproductive system.
Illustration by Frank Forney. © 2016 Cengage Learning®.

An erection occurs as a result of a combination of factors, both physical and mental. When a man becomes sexually aroused, his brain sends chemical signals such as epinephrine, norepinephrine *

Sometimes, even when a man is sexually aroused, he may have difficulty developing an erection. Other times, a man may achieve an erection, but it does not last long enough to allow him to engage in sexual intercourse. Usually this happens because of a problem with the extra blood flow the penis needs to maintain an erection.

What Causes Erectile Dysfunction?

A variety of physical and psychological or emotional issues can cause ED. Physical causes include damage to the nerves, arteries, smooth muscles, and fibrous tissues in the penis. Diseases and disorders that cause damage and can lead to ED include:

Psychological or emotional issues, such as the following, can also contribute to ED:

Lifestyle choices, such as smoking, drinking too much alcohol, using illegal drugs, being overweight, and not exercising, can also lead to ED.

Heart disease *

Erections begin in the brain. After some sort of physical or mental stimulation, the brain sends chemical signals along the body's nerve pathways to the penis. The muscle tissue in the penis begins to relax and the penis fills with blood, becoming erect. For some people with neurological conditions, these pathways become blocked, resulting in ED. Neurological conditions that can cause ED include Parkinson's disease * , multiple sclerosis, spinal cord and brain injuries, Alzheimer's (ALTS-hy-merz) disease * , and stroke * .

According to the American Urological Society, about 10 to 20 percent of all ED cases are related to psychological disorders. Because many of them are treatable, it is important for patients to discuss any emotional concerns they have with their physician. Often, therapy or medication may be helpful in resolving ED in these patients. Some common psychological causes of ED include stress, depression, anxiety, low self-esteem, and panic disorder. The issues may be related to sexual abuse or trauma as well.

Sometimes the use of different prescription and over-the-counter medications may be directly related to ED. Many of these medications contain ingredients that can interrupt blood flow or nerve impulses. Drug classes that may lead to ED include diuretics * , antihypertensive drugs, antidepressant medications * , anti-inflammatory drugs, muscle relaxers, and certain prostate cancer drugs. It is important for men to discuss with their doctor other medications that they are taking. Lifestyle choices that may lead to ED include obesity * and the abuse of alcohol and recreational drugs.

How Common Is Erectile Dysfunction?

Erectile dysfunction is common, especially among men aged 40 to 70 years. The likelihood of ED increases with age, however, the aging process does not cause ED. As of 2016, the National Institute of Diabetes and Digestive and Kidney Diseases estimated that ED occurs in about 12 percent of men younger than age 60, 22 percent of men age 60 to 69, and 30 percent of men age 70 or older. It is not contagious.

How Does a Man Know He Has Erectile Dysfunction?

Men who find it difficult to develop or maintain an erection at least 50 percent of the time may be diagnosed with ED.

How Do Doctors Diagnose and Treat Erectile Dysfunction?

Diagnosis Treatment

Fortunately, many treatments are available for men with ED. The treatment options range from simple to invasive, and with the guidance of a physician, each man can choose the option that is best for him.

In some cases, simple changes in lifestyle may resolve ED. Diet and exercise, stress reduction techniques, and avoidance of alcohol and drugs are all positive changes that can lead to more frequent and lasting erections.

ED medications such as sildenafil citrate (Viagra), tadalafil (Cialis), and vardenafil (Levitra) work by helping the muscles and vessels in the penis relax so that more blood can flow to them, which allows the penis to become erect. These drugs have been successful in treating ED for many men, but they can be dangerous when combined with other medications and should only be used according to the directions given by a physician.

Certain sexual aids can be helpful in achieving and maintaining erections. A penis pump works by creating a vacuum around the penis that encourages increased blood flow, allowing an erection. When an erection develops, a penis ring can be placed at the base of the shaft to maintain the erection by preventing the flow of blood back out of the penis.

Surgical intervention is also an option for men with ED. One type of surgical intervention involves the placement of a flexible rod in the penis that can be unfolded, making the penis erect and able to engage in sexual intercourse. Another option is the implantation of fluid-filled sacs that can be pumped up to create an erection.


After the introduction of Viagra in 1998, an alarming trend developed among young men who take ED medications recreationally. Although these young men do not have ED, they sometimes combine ED drugs with methylenedioxymethamphetamine (Ecstasy) and never really consider the dangerous and potentially deadly side effects. People using Viagra, Cialis, or Levitra for recreational purposes may experience a dangerous drop in blood pressure, painful erections that require medical intervention to reverse, and death. Studies have shown that these men also experience much greater rates of sexually transmitted diseases and HIV * /AIDS * .

See also Orchitis • Scrotal Swelling • Sexually Transmitted Infections (STIs): Overview • Testicular Torsion • Urinary Tract Infection


Books and Articles

Shamloul, Rany, and Hussein Ghanem. “Erectile Dysfunction.” The Lancet 381, no. 9861 (2013): 153–165.


Charnow, Jody A., ed. “Erectile Dysfunction Risk Not Lowered by Aspirin, Other NSAIDS.” Renal and Urology News. 2015. (accessed October 13, 2015).

MedlinePlus “Drugs That May Cause Impotence.” U.S. National Library of Medicine. (accessed October 13, 2015).


American Urological Association. 1000 Corporate Blvd., Linthicum, MD 21090. Toll-free (U.S. only): 1-866-RING AUA (1-866-7464282). Phone: 410-689-3700. Fax: 410-689-3800. Website: (accessed December 11, 2015).

National Institute of Diabetes and Digestive and Kidney Diseases. 9000 Rockville Pk., Bethesda, MD 20892-2560. Telephone: 301-496-3583. Website: (accessed July 26, 2016).

* semen (SEE-men) is the spermcontaining whitish fluid produced by the male reproductive tract.

* norepinephrine (NOR-e-pi-nefrin) is a body chemical that can increase the arousal response, heart rate, and blood pressure.

* heart disease is a broad term that covers many conditions that prevent the heart from working properly to pump blood throughout the body.

* Parkinson's disease is a disorder of the nervous system that causes shaking, rigid muscles, slow movements, and poor balance.

* Alzheimer's (ALTS-hy-merz) disease is a condition that leads to gradually worsening loss of mental abilities, including memory, judgment, and abstract thinking, as well as changes in personality.

* stroke is a brain-damaging event usually caused by interference with blood flow to and within the brain. A stroke may occur when a blood vessel supplying a region of the brain becomes clogged or bursts, depriving brain tissue of oxygen. As a result, nerve cells in the affected area of the brain, and the specific body parts they control, do not function properly function.

* diuretics (dye-yoor-EH-tiks) are medications that increase the body's output of urine.

* antidepressant medications are medications used for the treatment and prevention of depression.

* obesity (o-BEE-si-tee) is an excess of body fat. People are considered obese if they weigh more than 30 percent above what is healthy for their height.

* HIV or human immunodeficiency virus (HYOO-mun ih-myoono- dih-FIH-shen-see) is the virus that causes AIDS (acquired immunodeficiency syndrome), an infection that severely weakens the immune system.

* AIDS or acquired immunodeficiency (ihmyoo-no-dih-FIH-shensee) syndrome is an infection that severely weakens the immune system; it is caused by the human immunodeficiency virus (HIV).

* tumor (TOO-mor) is an abnormal growth of body tissue that has no known cause or physiologic purpose. A tumor may or may not be cancerous.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)