What Causes Erectile Dysfunction?

About 70 percent of cases of erectile dysfunction (ED) are thought to be caused by physical factors. However, after ED has developed, it’s easy to become anxious or frustrated. These types of feelings are thought to contribute to ED for about 80 percent of men.

Physical causes of ED can interfere with the:

• Initiation of an erection
• Ability of the erectile tissues in the penis to fill with arterial blood
• Ability of the erectile tissues in the penis to stay filled with blood

Many times, a physical cause will interfere with more than one aspect of an erection. Also, more than one physical cause may be present.

In older men, more than 80 percent of ED cases are thought to be caused by atherosclerosis, diabetes, and medication side effects.

It is possible for psychological factors to be the main cause of ED, for a minority of cases. One clue is being able to have erections while alone, but not with a partner.

Risk factors associated with ED

Studies have shown that men are at higher risk for erectile dysfunction (ED) if they:

• Are older
• Have poor overall health
• Have problems urinating, or other urinary tract symptoms
• Have high blood pressure, high cholesterol, diabetes, or other risk factors for cardiovascular disease
• Smoke cigarettes
• Have a diagnosis of heart disease that is being treated
• Are overweight
• Eat foods high in cholesterol or saturated fats
• Don’t exercise

Men who succeed in improving risk factors that can be changed – for example, by stopping smoking, losing weight and eating healthier foods – can reduce their risk for ED, as well as enjoy the benefits of improved health.

Problems initiating an erection

Any conditions that alter the way a man thinks about sexual activity, or that affect the brain, spinal cord, or the nerves leading directly to the penis, can interfere with the stimulation of an erection.  These can include:

• Head trauma
• Stroke
• Spinal cord injury - depending on the level of the injury, and whether it goes all the way through the spinal cord or spares some spinal tissue
• Parkinson’s disease or other degenerative diseases of the brain or spinal cord, such as multiple sclerosis
• Diabetes - which can damage nerves
• Hormone disorders - include overproduction of hormones, underproduction of hormones, or the lack of a normal response to hormones within the body.
  • Taking illegal steroids disrupts the normal production of hormones in the body and ends up interfering with many body functions, including erections
• Liver or renal failure
• Alcoholism or heavy drinking - can damage the nerves leading to the penis
• Vitamin B deficiency - can cause spinal cord or other nerve damage
• Pelvic surgery or traumatic pelvic injury - can damage nerves leading to the penis
• Surgery of organs near the penis, for example to treat prostate, bladder or rectal cancer or to treat prostate enlargement - can injure the nerves that stimulate the penis
• Irradiation of the pelvis to treat cancer - can injure nerves that stimulate the penis
• Nerve damage caused by putting too much weight on the body area just behind the penis, for example when bicycling for a long period of time - usually temporary if sitting posture is corrected
• Side effects of certain medications that alter nerve activity and/or brain chemistry, such as antidepressant medication, antipsychotic medication, sleeping pills, or tranquilizers
• Severe depression, severe anxiety disorders, schizophrenia, or other mental or emotional illnesses needing treatment
• Situation-specific depression, anxiety, anger, resentment, grief, or other emotions that make it difficult to have the desire for an erection, even if subconsciously

Problems with arterial blood flow

Any conditions that interfere with the flow of arterial blood to the erectile tissues to fill them with blood can prevent an erection. These can include:

• Atherosclerosis - can lead to fatty deposits on the walls of arteries, narrowing or obstruction of arteries supplying the penis, and problems with the mechanisms that allow small arteries and erectile tissue to expand and fill quickly with blood
• High blood pressure - can damage arterial vessels
• High cholesterol levels - can damage arterial vessels
• Cigarette smoking - can damage vessels, reduce arterial blood flow, and interfere with smooth muscle relaxation, a step necessary for developing an erection
• Diabetes - can damage arterial vessels
• Surgery of the pelvis - can damage arterial vessels
• Irradiation of the pelvis - can damage arterial vessels
• Traumatic injury that damages arterial vessels
• Side effects of medications, like drugs intended to lower blood pressure

Problems with keeping erectile tissues filled with blood

• Venous leakage - due to structural tissue damage, or because the erectile tissues don’t gain enough pressure quickly enough while filling with blood to flatten the veins and stop blood from leaking out
• Anxiety causing reflex increases in muscle contraction and hindering smooth muscle relaxation, making filling of erectile tissues less efficient and allowing leakage
• Peyronie’s disease (rare) causing degenerative changes to tissue and preventing erectile tissues from effectively flattening veins
• Direct traumatic injury to the penis, disrupting its structure and allowing blood to leak out through the veins

In addition, many medications can cause side effects leading to ED. Often, physicians can make adjustments in medications if they are told that side effects have become a problem.