Causes:

Over the past decades, the medical perspective on the causes of erectile dysfunction has shifted. Common wisdom used to attribute almost all cases of impotence to psychological factors. Now doctors believe that up to 85% of impotence cases are caused by medical or physical problems. Only 15% are completely psychologically based. Sometimes, erectile dysfunction is due to a combination of physical and psychological causes.

A number of medical conditions share a common problem with erectile dysfunction -- the impaired ability of blood vessels to open and allow normal blood flow.

Heart Disease, Atherosclerosis, and High Blood Pressure

Heart disease, atherosclerosis, high blood pressure and high cholesterol levels are major risk factors for erectile dysfunction. In fact, erectile problems may be a warning sign of these conditions in men at risk for atherosclerosis. Men who experience ED have a greater risk for angina, heart attack, or stroke. [For more information, see In-Depth Report #3: Coronary artery disease.]

Erectile dysfunction is a very common problem in men with high blood pressure. More than 40% of men with erectile dysfunction have hypertension. Many of the drugs used to treat hypertension (such as calcium channel blockers and beta-blockers) may also cause ED. [For more information, see In-Depth Report #14: High blood pressure.]

Diabetes

Diabetes is a major risk factor for erectile dysfunction. Between 30 - 50% of all men with diabetes report some form of sexual difficulty. Blocked arteries and nerve damage are both common complications of diabetes. When the blood vessels or nerves of the penis are involved, erectile dysfunction can result. Diabetes is also associated with heart disease and chronic kidney disease, other risk factors for ED. [For more information, see In-Depth Report #60: Diabetes type 2.]

Obesity

Obesity increases the risk for diabetes, heart disease, and erectile dysfunction.

Metabolic Syndrome

Metabolic syndrome -- a cluster of conditions that includes obesity and abdominal fat, unhealthy cholesterol and triglyceride levels, high blood pressure, and insulin resistance -- is also a risk factor for erectile dysfunction in men older than 50 years.

Benign Prostatic Hyperplasia

Surgery and drug treatments for benign prostatic hyperplasia, such as finasteride (Proscar), can also increase the risk for impotence. [For more information, see In-Depth Report #71: Benign prostatic hyperplasia.]

Neurologic Conditions

Diseases that affect the central nervous system can cause erectile dysfunction. These conditions include Parkinson's disease, multiple sclerosis, and stroke. [For more information, see In-Depth Reports #51: Parkinson's disease; #17: Multiple sclerosis; #45: Stroke.]

Endocrinologic and Hormonal Conditions

Low levels of the male hormone testosterone can be a contributing factor to erectile dysfunction in men who have other risk factors. (Low testosterone as the sole cause of erectile dysfunction affects only about 5% of men. In general, low testosterone levels are more likely to reduce sexual desire than to cause impotence.) Abnormalities of the pituitary gland that cause high levels of the hormone prolactin are also associated with erectile dysfunction. Other hormonal and endocrinologic causes of erectile dysfunction include thyroid and adrenal gland problems.

Physical Trauma and Injury

Spinal cord injury and pelvic trauma, such as a pelvic fracture, can cause nerve damage that results in impotence. Other conditions that can injure the spine and effect impotence include spinal cord tumors, spina bifida, and a history of polio.

Surgery

Surgery for Prostate Cancer. Radical prostatectomy can cause loss of sexual function. Nerve-sparing surgical procedures are proving to be helpful in reducing the risk of impotence. (Radiation treatments for prostate cancer also cause erectile dysfunction.) [For more information, see In-Depth Report # 33: Prostate cancer.]

Surgery for Colon and Rectal Cancers. Surgical and radiation treatments for colorectal cancers can cause impotence in some patients. In general, colostomy does not usually affect sexual function. However, wide rectal surgery can cause short-term or long-term sexual dysfunction. [For more information, see In-Depth Report #55: Colon and rectal cancers.]

Fistula Surgery. Surgery to repair anal fistulas can affect the muscles that control the rectum (external anal sphincter muscles), sometimes causing impotence. (Repair of these muscles may restore erectile function.)

Orthopedic Surgery. Erectile dysfunction can sometimes result from orthopedic surgery that affects pelvic nerves.

Note: Vasectomy does NOT cause erectile dysfunction.

Medications

Many medications increase the risk for erectile dysfunction. They include:

• High blood pressure medications, particularly diuretics, beta-blockers, and calcium-channel blockers.
• Heart or cholesterol medications such as digoxin, gemfibrozil, or clofibrate.
• Psychotropic medication used to treat depression and bipolar disorder such as selective serotonin-reuptake inhibitors (SSRIs), tricyclic antidepressants, monoamine oxidase inhibitors, and lithium. Certain types of antipsychotic medication, such as phenothiazines (like compazine) and butyrophenones (like haloperidol), can also cause erectile dysfunction.
• Gastroesophagelal reflux disorder (GERD) medications, used to reduce stomach acid, such as rantidine (Zantac) and cimetidine (Tagamet).
• Hormone drugs such as estrogens, corticosteroids, and 5-alpha reductase inhibitors.
• Chemotherapy drugs such as methotrexate.

Psychological Causes

Anxiety. Anxiety has both emotional and physical consequences that can affect erectile function. It is among the most frequently cited contributors to psychological impotence.

Stress. Even simple stress can affect sexual dysfunction.

Depression. Depression can reduce sexual desire and is associated with erectile dysfunction.

Relationship Problems. Troubles in relationships often have a direct impact on sexual functioning. Partners of men with erectile dysfunction may feel rejected and resentful, particularly if the affected man does not confide his own anxieties or depression. Tension and anger frequently arise between people who are unable to discuss sexual or emotional issues with each other. It can be very difficult for the man to perform sexually when both partners harbor negative feelings.