Conditions InDepth: Erectile Dysfunction (Impotence)

Erectile dysfunction, also called impotence, is the inability to attain or maintain an erection of the penis that is firm enough for penetration during sexual intercourse. To initiate and maintain an erection, the penis must fill with blood. Nerve signals stimulate this engorgement. They prompt the blood vessels in the penis to expand so blood can fill it. Meanwhile, other blood vessels constrict, trapping blood inside.

Male Genito-urinary System

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The following factors can cause erectile dysfunction:

Venous Leak: If the blood vessels (veins), which normally are compressed by the blood filling the penis during an erection, are not fully compressed, an erection may not be attainable, or may not last long. This can be caused by injury or diseases which prevent the full expansion of the vessels (arteries) which normally expand with blood.

Neurovascular Function: Erection cannot be attained if nerve signals do not prompt blood vessels to do their job or if blood flow to the penis is reduced. Nerve dysfunction can also diminish feeling in the penis, resulting in impotence. Many medications can cause erectile dysfunction by impairing either vascular or nerve function.

Medical conditions that can lead to neurovascular dysfunction include:

  • Diabetes: can interfere with nerve signals
  • Arteriosclerosis (hardening of the arteries): can reduce blood flow
  • Peripheral neuropathy , spinal cord injury, and surgery: can damage nerves

Psychological Factors: Psychological factors account for 10%-15% of erectile dysfunction cases. The brain initiates many of the nerve signals required for a successful erection. Problems in your relationship, feelings of guilt associated with sex, depression , anxiety , and stress can all lead to erectile dysfunction

Recent estimates suggest that roughly 20 million US men have erectile dysfunction. Erectile dysfunction increases with age, from about 5% at age 40, to 15%-25% at age 65 and older.

What are the risk factors for erectile dysfunction?
What are the symptoms of erectile dysfunction?
How is erectile dysfunction diagnosed?
What are the treatments for erectile dysfunction?
Are their screening tests for erectile dysfunction?
How can I reduce my risk of erectile dysfunction?
What questions should I ask my healthcare provider?
What is it like to live with erectile dysfunction?
Where can I get more information about erectile dysfunction?


Guay AT, Spark RF, Bansal S, et al. American Association of Clinical Endocrinologists medical guidelines for clinical practice for the evaluation and treatment of male sexual dysfunction: a couple’s problem. 2003 update. Endocr Pract. 2003;9:77-95.

National Institute of Diabetes & Digestive & Kidney Diseases website. Available at: .

National Library of Medicine website. Available at: .

Sivalingam S, Hashim H, Schwaibold H. An overview of the diagnosis and treatment of erectile dysfunction. Drugs. 2006;66:2339-2355.

Webber R. Erectile dysfunction. Clinical Evidence. 2005;13:1120-1127.

Last reviewed April 2007 by David Juan, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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