Causes of Erectile Dysfunction

To understand what causes erectile dysfunction or ED, it is important to first review how an erection occurs. For a man to have an erection, a complex process takes place within the body.

• An erection involves the central nervous system, the peripheral nervous system, psychological and stress-related factors, local factors with the erection bodies or the penis itself, as well as hormonal and vascular (blood flow or circulation) components. The penile portion of the process leading to an erection represents only a single component of a very complicated and complex process.
  
  
• Erections occur in response to touch, smell, and auditory and visual stimuli that trigger pathways in the brain. Information travels from the brain to the nerve centers at the base of the spine, where primary nerve fibers connect to the penis and regulate blood flow during erections and afterward.
  
  
• Sexual stimulation causes the release of chemicals from the nerve endings in the penis that trigger a series of events that ultimately cause muscle relaxation in the erection bodies of the penis. The smooth muscle in the erection bodies controls the flow of blood into the penis. When the smooth muscle relaxes, the blood flow dramatically increases, and the erection bodies become full and rigid, resulting in an erection. Venous drainage channels are compressed and close off as the erection bodies enlarge.
  
  
• Detumescence (the process by which the penis becomes flaccid) results when muscle-relaxing chemicals are no longer released.

If one or more of the above physical and/or psychological processes is disrupted, erectile dysfunction can result. Erectile dysfunction describes a man’s inability to achieve and maintain an erection of his penis sufficient for mutually satisfactory intercourse with his partner.

In general, the cause of erectile dysfunction is divided into 2 types: 

• Psychological (mental) causes
  
  
• Physical or organic (having to do with a bodily organ or an organ system) causes

Erection problems usually produce a significant psychological and emotional reaction in most men. This is often described as a pattern of anxiety and stress that can further interfere with normal sexual function. This "performance anxiety" needs to be recognized and addressed by your doctor.

For some men, erectile dysfunction develops with age or may be related to depression or another psychological cause, such as widower syndrome.

Certain feelings can interfere with normal sexual function, including feeling nervous about or self-conscious about sex; feeling stressed either at home or at work; or feeling troubled in your current relationship. In these cases, psychological counseling with you and your sexual partner may be successful. One episode of failure, regardless of cause, may propagate further psychological distress leading to further erectile failure.

In determining a physical (or organic) cause, your doctor will first rule out certain conditions, such as high blood pressure, high cholesterol, heart and vascular disease, low male hormone level, prostate cancer, and diabetes, which are associated with erectile dysfunction. In addition to these conditions, certain systemic and respiratory diseases are known to result in erectile dysfunction:

• Scleroderma (stiffening or hardening of the skin)
  
  
• Kidney failure
  
  
• Liver cirrhosis
  
  
• Hemachromatosis (too much iron in the blood)
  
  
• Chronic obstructive pulmonary disease

Often, one can restore sexual health by treating a condition such as high blood pressure with diet and/or exercise or by controlling diabetes or other chronic diseases. Nutritional states, including malnutrition and zinc deficiency, may be associated with erectile dysfunction and can also be treated with diet.

Almost any disease can affect erectile function by altering the nervous, vascular, or hormonal systems. Various diseases may produce changes in the smooth muscle tissue of the penis or influence mood and behavior.

• Diseases that affect the nervous system and are commonly associated with erectile dysfunction include:
  
  
  • Epilepsy
    
    
  • Stroke
    
    
  • Multiple sclerosis
    
    
  • Guillain-Barré syndrome
    
    
  • Alzheimer disease
    
    
  • Parkinson disease
    
    
• Vascular diseases account for nearly half of all cases of erectile dysfunction in men older than 50 years.
  
  
  • Vascular disease includes atherosclerosis (fatty deposits on the walls of the arteries, also called hardening of the arteries), a history of heart attacks, peripheral vascular disease (problems with blood circulation), and high blood pressure.
    
    
  • Prolonged tobacco use (smoking) is considered an important risk factor for erectile dysfunction because it is associated with poor circulation and its impact on cavernosal function.
    
    
  • Blood diseases, such as sickle cell anemia and leukemias, are also associated with erectile dysfunction.
    
    
• An imbalance in your hormones, such as testosterone, prolactin, or thyroid, can cause erectile dysfunction. The following hormonal (or endocrine) conditions are commonly associated with erectile dysfunction:
  
  
  • Hyperthyroidism (overactive thyroid gland)
    
    
  • Hypothyroidism (underactive thyroid gland)
    
    
  • Hypogonadism (leads to lower testosterone levels)

Medications used to treat other medical disorders may cause erectile dysfunction. If you think erectile dysfunction is caused by a medication, talk with your doctor about drugs that might not cause this side effect. Do not just stop taking a prescribed medication before talking with your doctor. Common medications associated with erectile dysfunction are: 

• Antidepressants (for depression)
  
  
• Antipsychotics (for psychological illness)
  
  
• Antihypertensives (for high blood pressure)
  
  
• Antiulcer drugs, such as cimetidine (Tagamet)
  
  
• Medications to treat prostate cancer, such as goserelin (Zoladex) and leuprolide (Lupron), and medications to treat benign enlargement of the prostate, such as finasteride (Proscar) and dutasteride (Avodart)
  
  
• Drugs that lower cholesterol (More studies are needed to determine if erectile dysfunction is actually due to the high cholesterol in the blood vessels or the drugs to lower the high cholesterol.)
  
  
• Alcohol abuse
  
  
• Mind-altering agents, such as marijuana and cocaine

Surgery in the pelvic area may injure the nerves and the arteries near the penis, resulting in erectile dysfunction. Also, surgical procedures on the brain and the spinal cord may cause erectile dysfunction. Those procedures often associated with erectile dysfunction include:

• Aortoiliac or aortofemoral bypass
  
  
• Abdominal perineal resection
  
  
• Proctocolectomy
  
  
• Radical prostatectomy
  
  
• Radiation therapy for prostate cancer as well as for other cancers, such as bladder cancer, colon cancer, or rectal cancer
  
  
• Brachytherapy (seed implants) for prostate cancer
  
  
• Cryosurgery of the prostate
  
  
• Cystectomy (removal of the urinary bladder)

Trauma or injury to the penis and/or the pelvic blood vessels and nerves is another potential factor in the development of erectile dysfunction.  

• Peyronie disease is a condition associated with erectile dysfunction. With this disease, scar tissue forms inside the penis, and the penis is usually bent or curved during an erection. Injuries to the penis may also result in scar tissue formation as well as penis curvature during an erection.
  
  
• Bicycle riding for long periods has also been implicated as a cause of erectile dysfunction. Some of the newer bicycle seats have been designed to soften pressure on the perineum (the soft area between the anus and the scrotum).

Currently, virtually any man who wishes to have an erection can obtain it, regardless of the underlying cause of his problem. Many reasonable treatment options exist. Your first step is to find a well-trained, experienced, and compassionate doctor who is willing to take the time to understand you as well as to fully examine you to discover the cause of erectile dysfunction. Together, you and your doctor can then discuss possible treatments.

American Urological Association
1000 Corporate Boulevard
Linthicum, MD 21090
(866) RING-AUA (746-4282)
 
American Foundation for Urologic Disease
1000 Corporate Boulevard, Suite 410
Linthicum, MD 21090
(410) 689-3990
 
National Kidney and Urologic Diseases Information Clearinghouse
3 Information Way
Bethesda, MD 20892-3580

|Web Links|

American Urological Association

American Foundation for Urologic Disease

Media file 1: The normal erection process.

Media type:  Illustration

causes of erectile dysfunction, ED, erectile dysfunction, male impotence, penis, prostate gland, erection, testosterone, male hormone, hormonal system, physical causes, organic causes, psychological causes, mental causes, sexual dysfunction, medications, Peyronie disease, Peyronie’s disease, high blood pressure, diabetes, prostate cancer, trauma to penis, injury to penis, vascular diseases, systemic diseases, diseases of nervous system

Author: Stephen W Leslie, MD, FACS, Founder and Medical Director of the Lorain Kidney Stone Research Center, Clinical Assistant Professor, Department of Urology, Medical College of Ohio.

Editors: Bradley Fields Schwartz, DO, FACS, Director, Center for Urologic Laparoscopy and Endourology, Associate Professor of Urology, Department of Surgery, Southern Illinois University; Mary L Windle, Pharm D, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Pharmacy Editor, .com, Inc; Martin I Resnick, MD, Lester Persky Professor and Chair, Department of Urology; Professor, Department of Oncology, Case Western Reserve University School of Medicine.