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The Underlying Causes of Erectile Dysfunction

from Family Medicine Net Guide Vol. 1, No. 2 (December, 2003)

Men are typically more reluctant to visit the doctor than women, and then it’s only for basic things such as checkups and minor aches and ailments. When it comes to the subject of erectile dysfunction (ED), men are notoriously reticent. Whether they are uncomfortable discussing this condition with their doctors and sexual partners due to lack of knowledge, feelings of inadequacy, the perception that they are being judged, or any of a number of other reasons, it's unfortunate. Especially since many medical breakthroughs have been made in the last few years so that most men suffering from ED can receive treatment that allows them to lead normal, healthy sex lives.

It all starts with communication, though, especially with a spouse or partner. Often, the best facilitator of effective communication is information. This article is intended to provide men and their partners with the facts on ED, including how it is defined, what causes it, how it’s diagnosed, and how it’s treated. And, since the affected man’s partner has just as much at stake, and can often be the means to get the man to go see his doctor.

ED Defined

Erectile dysfunction can be defined as “the repeated inability to get or keep an erection firm enough for sexual intercourse.” It can be characterized by the “total inability to achieve erection, an inconsistent ability to do so, or a tendency to sustain only brief erections.” The National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC) estimates that 5% of 40-year-old men, and between 15%-25% of men 65 years old and older, experience ED.

Often men never receive treatment because they're reluctant to discuss the subject with their doctor. Until recently, it was believed that the cause of ED was psychological; however, it’s now understood that in at least 75% of cases, it is a symptom of, or caused by, an underlying physical condition.

How Do I Know If I Have ED?

This site, from the University of Maryland Medicine, offers a helpful list of ways in which your physician can determine whether a patient is suffering from erectile dysfunction, noting that a “physician typically interviews the patient about many physical and psychological factors. The patient must be as frank as possible for his physician to make a diagnosis. He should not interpret these questions as pushy or too personal if he expects to obtain help. These questions are very relevant and important for determining the proper approach. Even when there is a clear physical cause for ED, relationships and psychological factors can also have an effect.”

The initial exam involves a medical and personal history that covers past and present medical problems, medications currently being taken, other factors, and sexual history which can help in determining the nature of the dysfunction by inquiring as to the frequency, quality, and duration of the patient’s erections, the specific circumstances when erectile dysfunctions occur, and other relevant details. The physician will also interview the patient’s sexual partner, as doing so “may help the physician to better decipher underlying causes and in turn better recommend treatment choices.”

Next is the physical exam including a study the patient’s genital area to determine the degree of response to physical stimulation (diminished or absent response could indicate a nervous component to ED), and also to check for prostate abnormalities. A physician may prescribe several laboratory tests to determine the nature and cause of a patient’s ED, including blood tests for hormonal imbalances and tests for other medical conditions that may be causing or contributing to ED (hypertension, diabetes, etc). Less invasive diagnostic methods include monitoring the frequency and duration of night-time erections (helpful in determining if ED has a psychological component), and measuring the penile brachial index (compares blood pressure in the penis with the blood pressure taken in the arm; useful in detecting decreased blood flow to the penis).

What Causes ED?

The majority of ED cases is caused either by an underlying physical disorder or disease, or develops as a side effect of a medication the patient is taking. This link explains that “impotence occurs when there is a problem with any of the systems needed to get or maintain an erection. The good news is that potency can usually be restored when a man is treated for underlying medical conditions.”

A common cause of ED is vascular disease; hardening of the arteries can affect the artery leading to the penis so that it cannot dilate enough to deliver enough blood to produce an erection. A second cause is diabetes; nearly one in every four men with ED has diabetes. The nerve deterioration and damage to blood vessels that often accompanies diabetes can also cause erectile dysfunction. Similarly, diseases that affect the nervous system, including Parkinson’s disease and multiple sclerosis, often play a role in this problem. ED can also be caused by surgery for cancer of the prostate, colon, bladder, or rectum since it's possible for the nerves and blood vessels that control erections to be damaged in the process of removing cancerous tissue (surgery for cancer of the prostate frequently results in ED of some severity). Other diseases and conditions that can cause ED include kidney disease, hypertension, and several neurological disorders.

Injury and trauma can also play a part in ED. The nerve supply to the penis is very delicate and complicated. A proper conduction of impulses along these is basic for the initiation and maintenance of an erection. It is these nerves that activate the arteries and the veins and alter the dynamics of blood flow within them.” Trauma or injury to the penis, spinal cord, pelvis, prostate, or bladder can result in damage to the nerves, blood vessels, and other tissues involved with blood flow to the penis,sending and relaying nerve signals associated with physical stimulation, and maintaining an erection.

Other possible factors in ED:

  • A side effect of many prescription and over-the-counter medications
  • Psychological and emotional factors, such as stress, anxiety, depression, and other mental triggers
  • Smoking
  • Inadequate levels of testosterone
  • Alcoholism or alcohol abuse

Treating ED

Medical professionals prefer to treat ED in stages, beginning with the least invasive methods first. Often the first step is to reduce the dosage of or eliminate entirely any prescription or over-thecounter medications that are known to cause or contribute to ED. Another treatment method is to devise a plan to reduce the stress and anxiety that can cause ED through the use of behavioral modification. But, as ED is most commonly caused by a physical disorder, treatment with oral medications is likely. This is the form of remedy that gets the most play in the media and is likely on the minds of many patients.

Viagra ( is the best known prescription medication for ED, first approved in 1998 and since prescribed to millions of men. Viagra works by increasing blood flow to the penis and should be taken approximately one hour prior to expected sexual activity; its effects persist for at least four hours. It is important to note that Viagra, contrary to a common misperception, is not an aphrodisiac and does not automatically cause erections; sexual excitement is still necessary for the patient to achieve an erection. Men taking nitrate-based medications, such as nitroglycerine for a heart condition, are advised not to use this form of therapy. Viagra's side effects can include headache, indigestion, facial flushing, and "blue vision" (basically just what it sounds like).

The recently approved medication Levitra ( is similar to Viagra; patients should take Levitra about an hour before sexual activity and-just as with Viagra-require some form of sexual stimulation to achieve erection. The most common side effects with Levitra are headache, flushing, stuffy or runny nose, indigestion, upset stomach, or dizziness.

A third drug, Cialis (, may also soon be approved and on the market. Cialis is differentiated from the other two ED medications by its longer-lasting effects (it has already earned the nickname "The Weekend Pill" in Europe, where it is already on the market). Side effects from Cialis are reported as similar to Viagra and Levitra, though some patients have also reported experiencing muscle aches and pain.

This site ( contains a chart offering a quick comparison of these three drugs. A fourth medication, Uprima, already approved in the UK and parts of Europe, may also be close to approval here in the US. It is a more rapid-acting ED medication that may centrally affect the brain to trigger an erection. There are also drugs available that can produce erections when they are injected into the penis, including papaverine hydrochloride, phentolamine, and alprostadil. These medications work by widening blood vessels, causing the penis to become engorged with blood, but may also "create unwanted side effects, however, including persistent erection (known as priapism) and scarring."

Other remedies available for men with erectile dysfunction who do not respond to medication therapy include several mechanical or prosthetic devices. One such option is an external vacuum pump device that draws blood into the penis by creating a partial vacuum and then, through the use of an elastic band, maintains the erection by preventing blood from flowing back out of the penis. Many men and their partners find this external prosthetic too bulky. In this case, a surgically implanted internal prosthesis may be more appealing.

There are two varieties: "malleable" implants consisting of twin rods that must be manually adjusted, and inflatable implants that use surgically-inserted cylinders filled with pressurized fluid by means of a small pump usually located under the scrotum (both the pump and fluid reservoir are also surgically implanted). And finally, there exist surgical procedures to repair obstructed arteries (penile arterial revascularization) that could cause ED, and also a procedure that intentionally blocks off veins that allow blood to exit the penis (venous ligation surgery), reducing blood leakage that diminishes the rigidity of the patient's erection. There are questions, however, regarding the safety and long-term effectiveness of this rarely performed procedure.

As you can see medical science has learned a great deal about the causes, diagnosis, and treatment of erectile dysfunction. Patients no longer need resign themselves to the "fact" that this condition is an unavoidable part of the aging process, or that there is nothing that can be done about it. The most important part of dealing with ED is communication, both between patients and their physicians and between patients and their partners. Through openness and honesty, men and their partners can reduce much of the fear, stress, and anxiety that often accompany ED, and, under a physician's care, begin treatment that will allow them to restore their sex life.