A man's penis becomes erect when one of his senses—sight, sound, taste, touch, or smell—is stimulated and he becomes aroused. His central nervous system sends nerve impulses that increase blood flow to his penis. As blood flows into the penis, the penis gets larger and harder. The blood vessels that drain blood from the penis are blocked enough so that blood stays in the penis, maintaining the erection.
For a man to have a normal erection, he needs to have an intact nervous system that receives external stimulus signals and sends arousal signals to the penis and an intact system of arteries and veins (vascular system) that allows blood to flow in and out of the penis.
Most erection problems are caused by a combination of both physical and psychological factors.
Physical causes of erection problems may include illnesses, injuries, or complications of surgery (such as removal of the prostate for cancer) that interfere with nerve impulses or blood flow to the penis. When the nervous system cannot transmit arousal signals, or when the blood vessels in the penis cannot fill or stay filled with blood, a man cannot have an erection.
Physical causes of erection problems include:
Psychological causes of erection problems include depression, anxiety, stress, grief, and problems with relationships. They interfere with the erection process by distracting the man from things that would normally arouse him or by lessening the effect they normally have on him.
Psychological issues account for about 40% of erection problems. Erection problems in men younger than 50 are more likely to be caused by psychological issues. Psychological causes of erection problems include the following:
Erectile dysfunction (impotence) refers to a man's inability to achieve or maintain an erection that is sufficient to have sexual intercourse. It does not mean lack of sexual interest or desire, and the man may or may not be able to have orgasms or ejaculate. Erectile dysfunction can occur at any age. Occasional episodes are considered normal and often do not mean there is a serious problem. Doctors prefer the term erectile dysfunction over impotence.
Erectile dysfunction can also be related to another medical condition, such as:
Many medicines can cause erectile dysfunction.
Medicines that cause an erection may be used for erectile dysfunction from physical problems. They also may be used along with counseling to treat erection problems that have psychological causes. Most men do not have serious side effects from these medicines. But if you have an erection that lasts longer than 3 hours, call your doctor immediately.
Last Revised: March 1, 2013
Author: Healthwise Staff
Medical Review: William H. Blahd, Jr., MD, FACEP - Emergency Medicine & David Messenger, MD
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