The goal of treating impotence is to enable a man to achieve and maintain an erection so that he can have sexual intercourse. Depending upon the cause of impotence, treatment may include one or more of the following.

Phosphodiesterase-5 inhibitors — Phosphodiesterase-5 (PDE-5) inhibitors work by increasing chemicals that allow the penis to become and remain erect. They help a man to achieve an erection after sexual stimulation, but the medication does not increase sexual desire.

PDE-5 inhibitors are effective in restoring potency in about 70 percent of men. They work best in men with psychogenic impotence, though can be used in men with other types of impotence as well. In men with conditions that affect the blood vessels (such as diabetes), PDE-5 inhibitors are effective in about 55 to 60 percent of cases. The success rate in men who have undergone prostate cancer surgery is between 25 and 30 percent.

Sildenafil — Sildenafil (Viagra®) should be taken one hour before planned sexual intercourse. Its effect lasts for about four hours; this refers to the time frame that erection is possible if sexual stimulation occurs, not the duration of the erection. The recommended dose is 50 mg for most men; men over the age of 65 should start with 25 mg. The dose may be increased up to 100 mg if the erection was unsatisfactory or decreased to 25 mg if there are bothersome side effects. Only one dose should be taken per 24 hours.

Vardenafil and tadalafil — Vardenafil (Levitra®) and tadalafil (Cialis®) are also PDE-5 inhibitors used to treat ED. Like sildenafil, men who take vardenafil may have an erection (in response to sexual stimulation) as soon as 30 minutes and for up to four hours after taking a vardenafil tablet (this refers to the time frame that erection is possible if sexual stimulation occurs, not the duration of erection). The recommended dose is 10 mg for most men; men over 65 years should start with 5 mg. The dose may be increased to 20 mg or decreased to 2.5 mg as needed. No more than one dose should be taken per 24 hours.

Men who take tadalafil may have an erection within 16 minutes (in response to sexual stimulation) and may be able to experience an erection (in response to sexual stimulation) up to 36 hours after each dose (this refers to the time frame that erection is possible, not the duration of erection). The recommended starting dose is 10 mg for most men. The dose may be increased to 20 mg or decreased to 5 mg as needed. No more than one dose should be taken every 24 hours. Tadalafil can also be taken every day as a low dose pill.

Use of PDE-5 inhibitors

Side effects — Side effects of PDE-5 inhibitors include headache, flushed (red) skin, indigestion, and dizziness. Sildenafil may cause distorted (blue-tinged) vision. Side effects are generally short-lived and resolve spontaneously.
Drug interactions — Men who use nitrates (nitroglycerin) in any form, either on a regular basis or only as needed for chest pain, should never use PDE-5 inhibitors. Taking PDE-5 inhibitors and nitrates can lead to dangerously low blood pressure. PDE-5 inhibitors do not cause heart attacks.
A man who has used a PDE-5 inhibitor and then develops cardiac problems and requires nitrate medications should NOT use the PDE-5 inhibitor in the future. Men who develop chest pain should contact their healthcare provider or go to an emergency department immediately.

Certain medications (including erythromycin, ketoconazole, protease inhibitors, rifampin, phenytoin, and grapefruit juice) can alter the duration of time that sildenafil, vardenafil, and tadalafil remain in the blood stream, which can cause additional side effects. A healthcare provider or pharmacist can provide specific information.

Medications such as doxazosin (Cardura®) and terazosin (Hytrin®), used to treat frequent urination and other urinary symptoms caused by an enlarged prostate (called benign prostatic hyperplasia or BPH), should not be taken with any of the PDE-5 inhibitors; the combination of drugs can cause very low blood pressure. However, tamsulosin (Flomax®), also prescribed for bothersome urinary symptoms caused by BPH, is safe to take with tadalafil as it does not cause a dangerous decline in blood pressure. It is not known if tamsulosin is safe to take with sildenafil or vardenafil. (See "Patient information: Benign prostatic hyperplasia (BPH) (Beyond the Basics)".)

Safety — It is not yet proven that sildenafil is safe for these groups:

Men who have had a heart attack, stroke, or life-threatening irregular heartbeats (called arrhythmia) within the last six months
Men with untreated low or high blood pressure
Men with retinitis pigmentosa, a progressive eye disorder that can lead to blindness
Resuming sexual activity after a prolonged period of inactivity is similar to beginning a new exercise routine. Men considering a PDE-5 medication should be able to participate in an activity that is approximately equal to the energy required for sex (eg, walking two to four miles per hour on a flat surface). The healthcare provider may recommend exercise treadmill testing to ensure that sexual activity will be safe.

Nonarteritic ischemic optic neuropathy or NAION, a condition associated with loss of vision, has been reported in a few men who have taken sildenafil and tadalafil. Most of these cases occurred in men with underlying nerve or blood vessel disease.

Purchasing medications for erectile dysfunction — A number of sources claim to sell medications such as Viagra®, Cialis®, Levitra®, or herbal supplements for erectile dysfunction through the internet or by mail for a reduced cost, often without a prescription. These sources are not known to be safe or reliable, and it is not possible to know whether the pills from these sources contain the actual drug or are counterfeit. Consumers are strongly cautioned to avoid potentially unreliable sources for any medication. Community pharmacies or reputable web-based pharmacies are the most reliable source for all types of medications.

Penile self-injection — With penile self-injection, the patient injects a medication (alprostadil or papaverine) into the corpora cavernosa (the two chambers of the penis that are filled with spongy tissue). This causes an erection by allowing the blood vessels within the penis to expand so that the penis first swells and then stiffens to create a fully rigid erection (figure 1). The erection created by penile injection occurs without sexual stimulation (different from the erection that occurs after sildenafil, vardenafil or tadalafil).

It takes a lot of training for men to feel comfortable with this type of therapy. Under the guidance of urologists, men are shown how to make the skin on the penis sterile and how to inject the medication properly (figure 2). Although this treatment works well for erections, many men eventually stop using it because of discomfort from the injections.

Side effects — Pain is the most common side effect. Men often say that this is the reason they discontinue this type of treatment.
There is also a small risk that the penis will remain erect after intercourse. This occurs in 6 percent of men who use alprostadil and about 11 percent of those who use papaverine. Prolonged erection, called priapism, that lasts longer than four to six hours is a medical emergency. A healthcare provider should be contacted immediately. An emergency procedure must be done as soon as possible to empty the blood that is trapped in the penis. An erection that lasts longer than 48 hours often results in scarring of the tissue inside the penis.

Intraurethral alprostadil (MUSE) — This treatment uses the same medication (alprostadil) as penile self-injection. Instead of injecting it, the man inserts a device with an alprostadil pellet into the urethra. The urethra is the opening in the center of the penis from which urine flows. The alprostadil is then absorbed into the erectile bodies (corpus cavernosum) to create an erection.

Side effects — Side effects include pain as the blood vessels in the penis widen and swell to create the erection. Problems like prolonged erection and scarring on the outside of the penis are less common than with self-injection therapy.
Vacuum-assisted erection devices — There are several products on the market that use vacuum pressure to draw blood into the penis. A rigid ring is placed at the base of the penis (near the body) to hold the blood inside the penis, allowing it to remain erect. Vacuum devices successfully create erections in as many as 67 percent of patients. Satisfaction with vacuum-assisted erections varies between 25 and 49 percent.

Vacuum-assisted devices require that a man be able to hold and pump the unit. It may take a week or more for the device to work effectively. After a man is accustomed to using the device, he can usually create an erection that is rigid enough for penetration and sexual intercourse. He will not be able to ejaculate because the ring that holds blood in the penis also compresses the urethra, preventing semen from exiting. The ability to have an orgasm is not affected by the ring.

Penile prostheses — A penile prosthesis is a device that is surgically implanted and inflates to allow the penis to become erect (figure 3). Penile prostheses are used less frequently because of the popularity of PDE-5 inhibitors and penile injection therapies. For men who do not respond to these therapies or who find vacuum erection therapy distasteful, penile prostheses are an option.

Side effects — Side effects of prosthetic devices include the possibility of infection, pain, and mechanical failure. Mechanical failure may require surgically removing the prosthesis and implanting a new one.
Testosterone replacement therapy — Testosterone therapy is prescribed if a man's testes do not make enough of the hormone testosterone. It is of no benefit in improving sexual function in men whose bodies make normal amounts of testosterone. Testosterone levels are determined with blood tests.

Men with low blood testosterone levels may have diminished libido (sex drive), erectile dysfunction (impotence), decreased muscle mass, increased fat, and are at increased risk for thinning of the bones (osteoporosis). Treatment is designed to increase a man's testosterone level, libido, erectile function, fat and muscle levels; bone density usually improve as testosterone levels return to normal.

Treatment options for testosterone deficient men include:

Testosterone injections — Testosterone injections of either testosterone cypionate (Depo-Testosterone®) or testosterone enanthate (Dela-Testryl®) increase the blood level of testosterone promptly. However, testosterone levels decline quickly; to sustain normal testosterone levels, injections must be given every one to two weeks. Pain at the injection site is the most common side effect.
Testosterone gels — Testosterone gel is applied daily to the skin surface, which allows the testosterone within the gel to be absorbed from the skin into the blood. One gel (Androgel®) is supplied as a foil packet; another (Testim ®) is in a small toothpaste-like tube. The gel is applied to the upper arms, near the shoulder, every morning. The gel dries quickly; blood testosterone levels increase within two hours and are stable for 24 hours.

Because testosterone gel applied to a man's skin surface can be transferred to a female partner's skin, men are cautioned to wear a shirt if sex is planned immediately after applying the gel. The gel is fully absorbed after two hours and the shirt precaution is not necessary after this time.
Testosterone skin patch — The testosterone patch (Androderm®) contains testosterone as well as a chemical enhancer that allows the testosterone to be absorbed through the skin into the blood. The patch is applied in the morning, usually after a shower, to the arm, or back, preferably in an area that has little to no hair (to enhance adhesion); the area where the patch is applied should be rotated. The patch must be changed every day. Side effects include skin irritation and a local rash.
Testosterone lozenge — A testosterone lozenge (Striant®) is placed in the mouth between the cheek and upper gums. It softens and forms a gel that adheres to the gums and remains in place for 12 hours; the testosterone is absorbed through the gums and into the bloodstream. It should be used twice daily and should not be chewed or swallowed. Any remaining gel should be removed before placing the next lozenge. Gum irritation and gingivitis (inflammation of the gums) occurs in a small percentage of men using this treatment.
Psychotherapy and psychoactive medications — Depression, anxiety, and distractions can cause erectile dysfunction. Often these problems can be treated using psychological counseling, antidepressant drugs, or both. Sexual therapy is sometimes needed as well.

Medications are used to treat both depression and anxiety. They are very effective, though some (especially those of the serotonin reuptake inhibitor (SSRI) class) can cause decreased sex drive and erectile dysfunction. On the other hand, some antidepressant drugs can cause delayed ejaculation, which can be helpful for men with premature ejaculation. (See "Patient information: Depression treatment options for adults (Beyond the Basics)".)

Psychological counseling or psychotherapy involves the patient talking to a therapist about his thoughts and concerns. Psychotherapy may be helpful for:

Couples, when one or both partners have a serious medical condition. Anxiety over the safety of sexual activity may be present in people who are ill and his or her partner.
Men who suddenly experience one or more erectile failures during attempted intercourse. This is called performance anxiety.
Men who are depressed. In this case, psychotherapy may be combined with an antianxiety or antidepressant medication. Almost all antidepressant medications are effective for improving symptoms of depression, but may cause sexual side effects (eg, erectile dysfunction).
Sex therapy — This type of therapy is often helpful for men who lack focus or become distracted during sex. Treatment focuses on encouraging both sexual partners to work together and uses structured home exercises to improve concentration.

Yohimbine — Yohimbine was once the only pill available to treat erectile dysfunction. It has been replaced with PDE-5 inhibitors, described above (see 'Phosphodiesterase-5 inhibitors' above).