Erectile dysfunction, sometimes called
"impotence," is the repeated inability to get or keep an erection firm enough
for sexual intercourse. The word "impotence" may also be used to describe other
problems that interfere with sexual intercourse and reproduction, such as lack
of sexual desire and problems with ejaculation or orgasm. Using the term
erectile dysfunction makes it clear that those other problems are not involved.
Figure 1. Arteries (top)
and veins (bottom) penetrate the long, filled cavities running the
length of the penis—the corpora cavernosa and the corpous sponglosum.
Erection occurs when relaxed muscles allow the corpora cavernosa to fill
with excess blood fed by the arteries, while drainage of blood through
the veins is blocked.
Erectile dysfunction, or ED, can be a total inability to achieve
erection, an inconsistent ability to do so, or a tendency to sustain only brief
erections. These variations make defining ED and estimating its incidence
difficult. Estimates range from 15 million to 30 million, depending on the
definition used. According to the National Ambulatory Medical Care Survey (NAMCS),
for every 1,000 men in the United States, 7.7 physician office visits were made
for ED in 1985. By 1999, that rate had nearly tripled to 22.3. The increase
happened gradually, presumably as treatments such as vacuum devices and
injectable drugs became more widely available and discussing erectile function
became accepted. Perhaps the most publicized advance was the introduction of the
oral drug sildenafil citrate (Viagra) in March 1998. NAMCS data on new drugs
show an estimated 2.6 million mentions of Viagra at physician office visits in
1999, and one-third of those mentions occurred during visits for a diagnosis
other than ED.
In older men, ED usually has a physical cause, such as
disease, injury, or side effects of drugs. Any disorder that causes injury to
the nerves or impairs blood flow in the penis has the potential to cause ED.
Incidence increases with age: About 5 percent of 40-year-old men and between 15
and 25 percent of 65-year-old men experience ED. But it is not an inevitable
part of aging.
ED is treatable at any age, and awareness of this fact has
been growing. More men have been seeking help and returning to normal sexual
activity because of improved, successful treatments for ED. Urologists, who
specialize in problems of the urinary tract, have traditionally treated ED;
however, urologists accounted for only 25 percent of Viagra mentions in 1999.
How does an erection occur?
The penis contains two chambers called the corpora cavernosa,
which run the length of the organ (see figure 1). A spongy tissue fills the
chambers. The corpora cavernosa are surrounded by a membrane, called the tunica
albuginea. The spongy tissue contains smooth muscles, fibrous tissues, spaces,
veins, and arteries. The urethra, which is the channel for urine and ejaculate,
runs along the underside of the corpora cavernosa and is surrounded by the
Erection begins with sensory or mental stimulation, or both.
Impulses from the brain and local nerves cause the muscles of the corpora
cavernosa to relax, allowing blood to flow in and fill the spaces. The blood
creates pressure in the corpora cavernosa, making the penis expand. The tunica
albuginea helps trap the blood in the corpora cavernosa, thereby sustaining
erection. When muscles in the penis contract to stop the inflow of blood and
open outflow channels, erection is reversed.
What causes ED?
Since an erection requires a precise sequence of events, ED
can occur when any of the events is disrupted. The sequence includes nerve
impulses in the brain, spinal column, and area around the penis, and response in
muscles, fibrous tissues, veins, and arteries in and near the corpora cavernosa.
Damage to nerves, arteries, smooth muscles, and fibrous
tissues, often as a result of disease, is the most common cause of ED.
Diseases—such as diabetes, kidney disease, chronic alcoholism, multiple
sclerosis, atherosclerosis, vascular disease, and neurologic disease—account for
about 70 percent of ED cases. Between 35 and 50 percent of men with diabetes
Also, surgery (especially radical prostate and bladder surgery
for cancer) can injure nerves and arteries near the penis, causing ED. Injury to
the penis, spinal cord, prostate, bladder, and pelvis can lead to ED by harming
nerves, smooth muscles, arteries, and fibrous tissues of the corpora cavernosa.
In addition, many common medicines—blood pressure drugs,
antihistamines, antidepressants, tranquilizers, appetite suppressants, and
cimetidine (an ulcer drug)—can produce ED as a side effect.
Experts believe that psychological factors such as stress,
anxiety, guilt, depression, low self-esteem, and fear of sexual failure cause 10
to 20 percent of ED cases. Men with a physical cause for ED frequently
experience the same sort of psychological reactions (stress,
Other possible causes are smoking, which affects blood flow in
veins and arteries, and hormonal abnormalities, such as not enough testosterone.
How is ED diagnosed?
Medical and sexual histories help define the degree and nature
of ED. A medical history can disclose diseases that lead to ED, while a simple
recounting of sexual activity might distinguish among problems with sexual
desire, erection, ejaculation, or orgasm.
Using certain prescription or illegal drugs can suggest a
chemical cause, since drug effects account for 25 percent of ED cases. Cutting
back on or substituting certain medications can often alleviate the problem.
A physical examination can give clues to systemic problems.
For example, if the penis is not sensitive to touching, a problem in the nervous
system may be the cause. Abnormal secondary sex characteristics, such as hair
pattern or breast enlargement, can point to hormonal problems, which would mean
that the endocrine system is involved. The examiner might discover a circulatory
problem by observing decreased pulses in the wrist or ankles. And unusual
characteristics of the penis itself could suggest the source of the problem—for
example, a penis that bends or curves when erect could be the result of
Several laboratory tests can help diagnose ED. Tests for
systemic diseases include blood counts, urinalysis, lipid profile, and
measurements of creatinine and liver enzymes. Measuring the amount of free
testosterone in the blood can yield information about problems with the
endocrine system and is indicated especially in patients with decreased sexual
Monitoring erections that occur during sleep (nocturnal penile
tumescence) can help rule out certain psychological causes of ED. Healthy men
have involuntary erections during sleep. If nocturnal erections do not occur,
then ED is likely to have a physical rather than psychological cause. Tests of
nocturnal erections are not completely reliable, however. Scientists have not
standardized such tests and have not determined when they should be applied for
A psychosocial examination, using an interview and a
questionnaire, reveals psychological factors. A man's sexual partner may also be
interviewed to determine expectations and perceptions during sexual intercourse.
How is ED treated?
Most physicians suggest that treatments proceed from least to
most invasive. Cutting back on any drugs with harmful side effects is considered
first. For example, drugs for high blood pressure work in different ways. If you
think a particular drug is causing problems with erection, tell your doctor and
ask whether you can try a different class of blood pressure medicine.
Psychotherapy and behavior modifications in selected patients
are considered next if indicated, followed by oral or locally injected drugs,
vacuum devices, and surgically implanted devices. In rare cases, surgery
involving veins or arteries may be considered.
Experts often treat psychologically based ED using techniques
that decrease the
Anxiety associated with intercourse. The patient's partner can
help with the techniques, which include gradual development of intimacy and
stimulation. Such techniques also can help relieve
Anxiety when ED from physical
causes is being treated.
Drugs for treating ED can be taken orally, injected directly
into the penis, or inserted into the urethra at the tip of the penis. In March
1998, the Food and Drug Administration (FDA) approved Viagra, the first pill to
treat ED. In August 2003, the FDA gave approval to a second oral medicine,
vardenafil hydrochloride (Levitra). Additional oral medicines are being tested
for safety and effectiveness.
Taken an hour before sexual activity, Viagra and Levitra work
by enhancing the effects of nitric oxide, a chemical that relaxes smooth muscles
in the penis during sexual stimulation and allows increased blood flow.
While oral medicines improve the response to sexual
stimulation, they do not trigger an automatic erection as injections do. The
recommended dose for Viagra is 50 mg, and the physician may adjust this dose to
100 mg or 25 mg, depending on the patient. The recommended dose for Levitra is
10 mg, and the physician may adjust this dose to 20 mg if 10 mg is insufficient.
Lower doses of 5 mg and 2.5 mg are available for patients who take other
medicines or have conditions that may decrease the body's ability to use Levitra.
Neither Viagra nor Levitra should be used more than once a
day. Men who take nitrate-based drugs such as nitroglycerin for heart problems
should not use either drug because the combination can cause a sudden drop in
blood pressure. Also, Levitra should not be taken with any of the drugs called
alpha-blockers, which are used to treat prostate enlargement or high blood
Oral testosterone can reduce ED in some men with low levels of
natural testosterone, but it is often ineffective and may cause liver damage.
Patients also have claimed that other oral drugs—including yohimbine
hydrochloride, dopamine and serotonin agonists, and trazodone—are effective, but
the results of scientific studies to substantiate these claims have been
inconsistent. Improvements observed following use of these drugs may be examples
of the placebo effect, that is, a change that results simply from the patient's
believing that an improvement will occur.
Many men achieve stronger erections by injecting drugs into
the penis, causing it to become engorged with blood. Drugs such as papaverine
hydrochloride, phentolamine, and alprostadil (marketed as Caverject) widen blood
vessels. These drugs may create unwanted side effects, however, including
persistent erection (known as priapism) and scarring. Nitroglycerin, a muscle
relaxant, can sometimes enhance erection when rubbed on the penis.
A system for inserting a pellet of alprostadil into the
urethra is marketed as Muse. The system uses a prefilled applicator to deliver
the pellet about an inch deep into the urethra. An erection will begin within 8
to 10 minutes and may last 30 to 60 minutes. The most common side effects are
aching in the penis, testicles, and area between the penis and rectum; warmth or
burning sensation in the urethra; redness from increased blood flow to the
penis; and minor urethral bleeding or spotting.
Research on drugs for treating ED is expanding rapidly.
Patients should ask their doctor about the latest advances.
Mechanical vacuum devices cause erection by creating a partial
vacuum, which draws blood into the penis, engorging and expanding it. The
devices have three components: a plastic cylinder, into which the penis is
placed; a pump, which draws air out of the cylinder; and an elastic band, which
is placed around the base of the penis to maintain the erection after the
cylinder is removed and during intercourse by preventing blood from flowing back
into the body (see figure 2).
Figure 2. A
vacuum-constrictor device causes an erection by creating a partial
vacuum around the penis, which draws blood into the corpora cavernosa.
Pictured here are the necessary components: (a) a plastic cylinder,
which covers the penis; (b) a pump, which draws air out of the cylinder;
and (c) an elastic ring, which, when fitted over the base of the penis,
traps the blood and sustains the erection after the cylinder is removed.
One variation of the vacuum device involves a semirigid rubber
sheath that is placed on the penis and remains there after erection is attained
and during intercourse.
Hope Through Research
Advances in suppositories, injectable medications, implants,
and vacuum devices have expanded the options for men seeking treatment for ED.
These advances have also helped increase the number of men seeking treatment.
Gene therapy for ED is now being tested in several centers and may offer a
long-lasting therapeutic approach for ED.
The National Institute of Diabetes and Digestive and Kidney
Diseases (NIDDK) sponsors programs aimed at understanding the causes of erectile
dysfunction and finding treatments to reverse its effects. NIDDK's Division of
Kidney, Urologic, and Hematologic Diseases supported the researchers who
developed Viagra and continue to support basic research into the mechanisms of
erection and the diseases that impair normal function at the cellular and
molecular levels, including diabetes and high blood pressure.
Points to Remember
Erectile dysfunction (ED) is the repeated
inability to get or keep an erection firm enough for sexual intercourse.
ED affects 15 to 30 million American men.
ED usually has a physical cause.
ED is treatable at all ages.
- Treatments include
psychotherapy, drug therapy, vacuum devices, and surgery.
National Institutes of Health (NIH)
Nutritional and Herbal Therapy for
- The Chinese herbal formula,
Nine Seeds Return to
Spring Pill, is very helpful for impotence.
The following foods, according to the
Tao of Nutrition, can help with impotence:
- sea cucumber
- bitter melon seeds
- black beans
- kidney beans
- lycii fruit
- Lamb stew with daikon radish and Chinese black dates.
- Drink a tea made with walnuts, lotus seeds, pearl barley,
Chinese black dates and lycii fruit. Drink three times daily.
- Roast and grind bitter melon seeds and take one teaspoon
three times daily with some rice wine.
Tao of Nutrition, by Maoshing Ni, Ph.D., C.A., and Cathy McNease,