Erectile dysfunction is the inability to maintain an erection sufficient for sexual intercourse at least 25 percent of the time.

An occasional inability to maintain an erection happens to most men and is normal. But ongoing erection problems are a sign of erectile dysfunction and should be evaluated. In some cases, erectile dysfunction is the first sign of another underlying health condition that needs treatment.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Male sexual arousal is a complex process involving the brain, hormones, emotions, nerves, muscles and blood vessels. If something affects any of these systems — or the delicate balance among them — erectile dysfunction can result.

Anatomy of an erection
The penis contains two cylindrical, sponge-like structures (corpus cavernosum) that run along its length, parallel to the tube that carries semen and urine (urethra).

When a man becomes sexually aroused, nerve impulses cause the blood flow to the cylinders to increase several times the normal amount. This sudden influx of blood expands the sponge-like structures and produces an erection by straightening and stiffening the penis.

Continued sexual arousal maintains the higher rate of blood flow into the penis and limits the blood flow out of the penis, keeping the penis firm. After ejaculation or when the sexual excitement passes, the excess blood drains out of the spongy tissue, and the penis returns to its nonerect size and shape.

Physical causes of erectile dysfunction
At one time, doctors thought erectile dysfunction was primarily caused by psychological issues. But this isn't true. While thoughts and emotions always play a role in getting an erection, erectile dysfunction is usually caused by something physical, such as a chronic health problem or the side effects of a medication. Sometimes a combination of things causes erectile dysfunction.

Common causes of erectile dysfunction include:

• Heart disease
• Clogged blood vessels (atherosclerosis)
• High blood pressure
• Diabetes
• Obesity
• Metabolic syndrome

Other causes of erectile dysfunction include:

• Certain prescription medications
• Tobacco use
• Alcoholism and other forms of drug abuse
• Treatments for prostate cancer
• Parkinson's disease
• Multiple sclerosis
• Hormonal disorders such as low testosterone (hypogonadism)
• Peyronie's disease
• Surgeries or injuries that affect the pelvic area or spinal cord

In some cases, erectile dysfunction is one of the first signs of an underlying medical problem.

Psychological causes of erectile dysfunction
The brain plays a key role in triggering the series of physical events that cause an erection, beginning with feelings of sexual excitement. A number of things can interfere with sexual feelings and lead to — or worsen — erectile dysfunction. These can include:

• Depression
• Anxiety
• Stress
• Fatigue
• Poor communication or conflict with your partner

The physical and psychological causes of erectile dysfunction interact. For instance, a minor physical problem that slows sexual response may cause anxiety about maintaining an erection. The resulting anxiety can worsen erectile dysfunction.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

A variety of risk factors can contribute to erectile dysfunction. They include:

• Getting older. As many as 80 percent of men 75 and older have erectile dysfunction. Many men begin to notice changes in sexual function as they get older. Erections may take longer to develop, may not be as rigid or may take more direct touch to the penis to occur. But erectile dysfunction isn't an inevitable consequence of normal aging. Erectile dysfunction often occurs in older men mainly because they're more likely to have underlying health conditions or take medications that interfere with erectile function.
• Having a chronic health condition. Diseases of the lungs, liver, kidneys, heart, nerves, arteries or veins can lead to erectile dysfunction. So can endocrine system disorders, particularly diabetes. The accumulation of deposits (plaques) in your arteries (atherosclerosis) also can prevent adequate blood from entering your penis. And in some men, erectile dysfunction may be caused by low levels of testosterone (male hypogonadism).
• Taking certain medications. A wide range of drugs — including antidepressants, antihistamines and medications to treat high blood pressure, pain and prostate cancer — can cause erectile dysfunction by interfering with nerve impulses or blood flow to the penis. Tranquilizers and sleeping aids also can pose a problem.
• Certain surgeries or injuries. Damage to the nerves that control erections can cause erectile dysfunction. This damage can occur if you injure your pelvic area or spinal cord. Surgery to treat bladder, rectal or prostate cancer can increase your risk of erectile dysfunction.
• Substance abuse. Chronic use of alcohol, marijuana or other drugs often causes erectile dysfunction and decreased sexual drive.
• Stress, anxiety or depression. Other psychological conditions also contribute to some cases of erectile dysfunction.
• Smoking. Smoking can cause erectile dysfunction because it restricts blood flow to veins and arteries. Men who smoke cigarettes are much more likely to develop erectile dysfunction.
• Obesity. Men who are obese are much more likely to have erectile dysfunction than are men at a normal weight.
• Metabolic syndrome. This syndrome is characterized by belly fat, unhealthy cholesterol and triglyceride levels, high blood pressure, and insulin resistance.
• Prolonged bicycling. Over an extended period, pressure from a bicycle seat has been shown to compress nerves and blood flow to the penis, leading to temporary erectile dysfunction and penile numbness.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

If erectile dysfunction is more than a temporary, short-term problem, see your doctor. Your own doctor, or a doctor specializing in erectile dysfunction, can help you determine the underlying cause or causes of erectile dysfunction and then help you find the right type of treatment.

Although you might view erectile dysfunction as a personal or embarrassing problem, it's important to seek treatment. In most cases, erectile dysfunction can be successfully treated. Also, see your doctor if the therapy or medication prescribed to treat erectile dysfunction isn't working for you. Don't try to combine medications or therapies on your own or make changes from prescribed doses.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Your doctor will ask questions about how and when your symptoms developed, what medications you take and any other physical conditions you might have. Your doctor will also want to discuss recent physical or emotional changes.

If your doctor suspects that physical causes are involved, he or she will likely want to take blood tests to check your level of male hormones and for other potential medical problems, such as diabetes. Your doctor may also want to try eliminating or replacing certain prescription drugs you're taking one at a time to see whether any are responsible for erectile dysfunction.

More specialized tests may include:

• Ultrasound. This test can check blood flow to your penis. It involves using a wand-like device (transducer) held over the blood vessels that supply the penis. The transducer emits sound waves that pass through body tissues and reflect back, producing an image to let your doctor see if your blood flow is impaired. The test often is done before and after injection of medication into the side of the penis to see if there's an improvement in blood flow.
• Neurological evaluation. Your doctor usually assesses possible nerve damage by conducting a physical examination to test for normal touch sensation in your genital area.
• Dynamic infusion cavernosometry and cavernosography (DICC). This procedure involves injecting a dye into penile blood vessels to permit your doctor to view any possible abnormalities in blood pressure and flow into and out of your penis. It's generally done with local anesthesia by a urologist who specializes in erectile dysfunction.
• Nocturnal tumescence test. If your doctor suspects that mainly nonphysical causes are to blame, he or she may ask whether you obtain erections during masturbation, with a partner or while you sleep. Most men experience many erections, without remembering them, during sleep. A simple test that involves wrapping a special perforated tape around your penis before going to sleep can confirm whether you have erections while you're sleeping. If the tape is separated in the morning, your penis was erect at some time during the night. Tests of this type confirm that there is not a physical abnormality causing erectile dysfunction, and that the cause is likely psychological.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

A variety of options exist for treating erectile dysfunction. They range from medications and simple mechanical devices to surgery and psychological counseling. The cause and severity of your condition are important factors in determining the best treatment or combination of treatments for you.

Cost
You and your partner may want to talk with your doctor about how much money you're willing to spend and your preferences. Treatment for erectile dysfunction can be costly and insurance coverage varies. Because erectile dysfunction can by a sign of a number of underlying health conditions, initial evaluation of the problem is covered by most insurance policies. Medications or other treatments for erectile dysfunction may or may not be covered by your policy — check with your insurance provider to find out. Many policies have a limit on how many pills or injections are covered per month. Standard Medicare prescription drug coverage doesn't cover medications for erectile dysfunction.

Oral medications
Oral medications available to treat ED include:

• Sildenafil (Viagra)
• Tadalafil (Cialis)
• Vardenafil (Levitra)

All three medications work in much the same way. Chemically known as phosphodiesterase inhibitors, these drugs enhance the effects of nitric oxide, a chemical that relaxes muscles in the penis. This increases the amount of blood flow and allows a natural sequence to occur — an erection in response to sexual stimulation.

These medications don't automatically produce an erection. Instead they allow an erection to occur after physical and psychological stimulation. Many men experience improvement in erectile function after taking these medications regardless of the cause of their impotence.

These medications share many similarities, but they have differences as well. They vary in dosage, duration of effectiveness and possible side effects. Other distinctions — for example, which drug is best for certain types of men — aren't yet known. No study has directly compared these three medications.

Not all men benefit
Although these medications can help many people, not all men can or should take them to treat erectile dysfunction. You should not take these medications if:

• You take nitrate drugs for angina, such as nitroglycerin (Nitro-Bid, others), isosorbide mononitrate (Imdur) and isosorbide dinitrate (Isordil)
• You take a blood-thinning (anticoagulant) medication
• You take certain types of alpha blockers for enlarged prostate (benign prostatic hyperplasia) or high blood pressure

Viagra, Levitra or Cialis may not be a good choice for you if:

• You have severe heart disease or heart failure
• You've had a stroke
• You have very low blood pressure (hypotension)
• You have uncontrolled high blood pressure (hypertension)
• You have uncontrolled diabetes

Don't expect these medications to fix your erectile dysfunction immediately.

Work with your doctor to find the right treatment and dose for you. Dosages may need adjusting. Or you may need to alter when you take the medication.

Before taking any medication — including Viagra, Levitra or Cialis — make sure to discuss with your doctor:

• Potential benefits and side effects of the medication you are considering
• Any illnesses or serious health problems you have now or have had in the past
• Any prescription or over-the-counter medications you take (including herbal remedies)

Prostaglandin E (alprostadil)
Two treatments involve using a drug called alprostadil. Alprostadil is a synthetic version of the hormone prostaglandin E. The hormone helps relax muscle tissue in the penis, which enhances the blood flow needed for an erection. There are two ways to use alprostadil:

• Needle-injection therapy. With this method, you use a fine needle to inject alprostadil (Caverject, Edex) into the base or side of your penis. This generally produces an erection in five to 20 minutes that lasts about an hour. Because the injection goes directly into the spongy cylinders that fill with blood, alprostadil is an effective treatment for many men. And because the needle used is so fine, pain from the injection site is usually minor. Other side effects may include bleeding from the injection, prolonged erection and formation of fibrous tissue at the injection site. The cost per injection can be expensive. Injecting a mixture of alprostadil and other prescribed drugs may be a less expensive and more effective option. These other drugs may include papaverine and phentolamine.
• Self-administered intraurethral therapy (Muse). This treatment involves using a disposable applicator to insert a tiny alprostadil suppository, about half the size of a grain of rice, into the tip of your penis. The suppository, placed about two inches into your urethra, is absorbed by erectile tissue in your penis, increasing the blood flow that causes an erection. Although needles aren't involved, you may still find this method painful or uncomfortable. Side effects may include pain, minor bleeding in the urethra, dizziness and formation of fibrous tissue.

Hormone replacement therapy
For the small number of men who have testosterone deficiency, testosterone replacement therapy may be an option.

Penis pumps
This treatment involves the use of a hollow tube with a hand-powered or battery-powered pump. The tube is placed over the penis, and then the pump is used to suck out the air. This creates a vacuum that pulls blood into the penis. Once you achieve an adequate erection, you slip a tension ring around the base of your penis to maintain the erection. You then remove the vacuum device. The erection typically lasts long enough for a couple to have sex. You remove the tension ring after intercourse.

Vascular surgery
This treatment is usually reserved for men whose blood flow has been blocked by an injury to the penis or pelvic area. Surgery may also be used to correct erectile dysfunction caused by vascular blockages. The goal of this treatment is to correct a blockage of blood flow to the penis so that erections can occur naturally. But the long-term success of this surgery is unclear.

Penile implants
This treatment involves surgically placing a device into the two sides of the penis, allowing erection to occur as often and for as long as desired. The inflatable device allows you to control when and how long you have an erection, the semirigid rods keep the penis in a rigid state all the time. These implants consist of either an inflatable device or semirigid rods made from silicone or polyurethane. This treatment is often expensive and is usually not recommended until other methods have been considered or tried first. As with any surgery, there is a small risk of complications such as infection.

Psychological counseling and sex therapy
If stress, anxiety or depression is the cause of your erectile dysfunction, your doctor may suggest that you, or you and your partner, visit a psychologist or counselor with experience in treating sexual problems (sex therapist). Even if it is caused by something physical, erectile dysfunction can create stress and relationship tension. Counseling can help, especially when your partner participates.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Although most men experience episodes of erectile dysfunction from time to time, you can take these steps to decrease the likelihood of occurrences:

• Work with your doctor to manage conditions that can lead to erectile dysfunction, such as diabetes and heart disease.
• Limit or avoid the use of alcohol.
• Avoid illegal drugs such as marijuana.
• Stop smoking.
• Exercise regularly.
• Reduce stress.
• Get enough sleep.
• Get help for anxiety or depression.
• See your doctor for regular checkups and medical screening tests.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Whether the cause is physical factors or psychological factors or a combination of both, erectile dysfunction can become a source of mental and emotional stress for a man — and his partner. If you experience erectile dysfunction only on occasion, try not to assume that you have a permanent problem or to expect it to happen again during your next sexual encounter. Don't view one episode of erectile dysfunction as a lasting comment on your health, virility or masculinity.

In addition, if you experience occasional or persistent erectile dysfunction, remember your sexual partner. Your partner may see your inability to have an erection as a sign of diminished sexual desire. Your reassurance that this is not the case can help.

Try to communicate openly and honestly about your condition. Treatment is often more successful if couples work together as a team. You may even want to see a counselor with your partner. This can help you address concerns you both have about erectile dysfunction and can be an effective treatment.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Several alternative treatments are being investigated for potential to alleviate erectile dysfunction, but their safety and effectiveness are not proved. They include:

• Acupuncture
• DHEA, a hormone that's a building block for testosterone
• Ginkgo
• L-arginine

Like mainstream medications and treatments, these alternative approaches also have risks and side effects — especially for men who have chronic health problems or take other medications.

Some alternative products that claim to work for erectile dysfunction can be dangerous. The Food and Drug Administration (FDA) has issued warnings about several "herbal Viagras" including True Man, Energy Max, Rhino Max, Rhino VMax and Libidus. These contain potentially harmful drugs that aren't listed on the label. These drugs can interact with prescription drugs and cause dangerously low blood pressure. These products are especially dangerous for men who take prescription drugs that contain nitrates.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.