Related Terms

• Adrenal gland, Alzheimer's disease, atherosclerosis, axillary, bulbocavernosus reflex test, cavernosography, cavernosometry, climax, coronary heart disease (CAD), corpora cavernosa, corpus spongiosum, diabetes, digital rectal examination (DRE), duplex ultrasound, ejaculate, erection, fibrous, glans, gynecomastia, hyperprolactinemea, hypogonadism, impotence, intraurethral, libido, Medicated Urethral System for Erection (MUSE), multiple sclerosis, neuropathy, nitrates, nitric oxide, nocturnal penile tumescence (NPT), orgasm, paraplegia, Parkinson's disease, penile biothesiometry, Peyronie's disease, pituitary gland, plaque, prolactin, quadriplegia, seminal fluid, sexual intercourse, sperm, stroke, substance abuse, testosterone, tunica albuginea, urethra, vascular, vascular reconstructive, surgery, vasoactive, venous leak.

Background

• Erectile dysfunction (ED), sometimes called impotence, is the repeated inability to get or keep an erection firm enough for sexual intercourse. 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.

• Estimates suggest that between 15 and 30 million (20-40%) Americans suffer from ED. There are approximately 26 new cases annually of ED in the United States per 1,000 population in men 40 to 69 years of age. Over 150 million men worldwide suffer from ED.

• Although ED is more common in men older than 65, it can occur at any age. An occasional episode of erectile dysfunction happens to most men and is normal. As men age, it is also normal to experience changes in erectile function. Erections may take longer to develop, may not be as rigid or may require more direct stimulation to be achieved. Men may also notice that orgasms are less intense, the volume of ejaculate is reduced, and recovery time increases between erections.

• Erection: The penis (male sexual organ) contains two chambers called the corpora cavernosa, which run the length of the penis shaft. 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. Erection begins with sensory or mental stimulation (either touch or image), 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.

Risk Factors and Causes

• Lifestyle choices: Lifestyle choices that contribute to heart disease and vascular problems also raise the risk of erectile dysfunction. Since an erection is dependent upon proper blood flow in the penis, heart diseases and vascular (blood vessel) problems that inhibit blood flow may contribute to erectile dysfunction (ED). Smoking, being overweight, eating unhealthy foods (such as a high fat diet), and avoiding exercise are related to an increase in symptoms of ED.

• Smoking: Smoking is perhaps the most significant risk factor for developing ED. Cigarette smoking can repeatedly produce a temporary rise in blood pressure (BP), restricting blood flow to various areas of the body including the penis. When the blood vessels in the pelvic and groin area are narrowed, that contributes to reduced penile blood flow. The more that is smoked, the more the chances for developing erectile dysfunction, especially in men over 50 years of age. Men who smoke more than 20 cigarettes daily have a 60% higher risk of ED, compared to men who never smoke. Among men who have never smoked, 12% have had erection problems.

• Physical diseases and disorders: Chronic (long term) diseases of the lungs, liver, kidneys, heart, nerves, arteries, or veins are risk factors for developing ED. Endocrine system disorders, particularly diabetes, may contribute to ED. Prostate gland enlargement, such as with benign prostatic hyperplasia (BPH), can also cause symptoms of ED by placing pressure on the blood vessels that fill the penis to cause an erection. A condition called atherosclerosis, or the accumulation of plaque deposits in the arteries, may also prevent the amount of blood necessary to maintain an erection from entering the penis. In some men, erectile dysfunction may be caused by low levels of the hormone testosterone. In some instances, ED may be one of the first signs of an underlying medical problem; physical diseases account for about 70% of the ED cases.

• Diabetes: ED occurs more often in those with diabetes. Diabetes can cause a condition called neuropathy, which is damage to the nerves throughout the body, including the penis. Damaged nerves cannot communicate properly with the brain. So even though sexual stimulation occurs, nerve damage prevents the information from being relayed to the penis, and it does not become erect. In addition, poor blood sugar control can inhibit nitric oxide production. Lack of nitric oxide can prevent the pressure of blood in the corpora cavernosa (chambers in the penis containing blood vessels) from rising enough to close off penile veins, allowing blood to flow out of the penis instead of remaining trapped for an erection. Blood vessels can also become narrowed or hardened (atherosclerosis) by conditions that often accompany diabetes, such as coronary heart disease (CAD). When atherosclerosis occurs in arteries that supply the penis or pelvic area, sexual function may be disrupted.

• As many as 60-80% of men with diabetes develop ED, compared to about 22- 25% of men without diabetes. ED most frequently develops after age 65, but in men with diabetes, it tends to occur 10-15 years earlier, on average. Men with diabetes may experience ED as early as age 30. The longer an individual has lived with diabetes, and the more uncontrolled it is, the more likely they are to develop ED.

• Vascular disease: Atherosclerosis (hardening and narrowing of the arteries) and hypertension (high blood pressure) cause a reduction in blood flow throughout the body and can lead to ED. Vascular problems during an erection are associated with age and accounts for 50-60% of ED in men over 60. Risk factors for atherosclerosis include smoking, diabetes, high blood pressure, and high cholesterol. Developing ED can be an indication for risk for coronary heart disease (CHD).

• Surgery or trauma: Damage to the nerves that control erections can cause erectile dysfunction. It may result from an injury to the pelvic area or spinal cord. Surgery to treat bladder, rectal, or prostate cancer also can result in erectile dysfunction due to possible damage to sensitive nerves and blood vessels in the area.

• Neurologic conditions: Spinal cord and brain injuries such as paraplegia (lower part of the body is paralyzed), quadriplegia (paralysis of both limbs), and stroke (lack of blood flow and oxygen to the brain that causes nerve and blood vessel damage) can cause impotence when they interrupt the transfer of nerve impulses from the brain to the penis causing ED. Other nerve disorders, such as multiple sclerosis (MS, an autoimmune disease that affects the nervous system), Parkinson's disease (a degenerative disorder of the nervous system causing uncontrollable shaking), and Alzheimer's disease (a brain disorder characterized by dementia), may also result in ED.

• Hormone disorders: Hormone disorders account for fewer than five percent of cases of ED. Testosterone (male hormone) deficiency, which occurs rarely, can result in a loss of libido (sexual desire) and loss of erection. An excess of the hormone prolactin, caused by a pituitary gland tumor, can reduce levels of testosterone and cause ED. Hormone imbalances can also result from kidney or liver disease, causing ED.

• Peyronie's disease: Peyronie's disease is a rare inflammatory condition that causes scarring of erectile tissue; normal skin cells are replaced by scar tissue. Scarring produces curvature of the penis that can interfere with sexual function, cause painful erections, and even block some of the blood flow.

• Venous leak: If the veins and muscles in the penis cannot prevent blood from leaving the penis during sexual arousal, an erection cannot be maintained. Venous leak can be a result of injury, disease, or damage to the veins in the penis and cause ED.

• Psychological conditions: Psychological conditions, such as performance anxiety, stress, guilt, worry, anxiety, or depression, also contribute to loss of sexual drive (libido) and may result in ED. Approximately 10-20% of ED cases can be contributed to psychological conditions. If an individual experiences loss of erection during sexual intercourse, he may worry that it will happen again. This can produce anxiety associated with performance and may lead to ED during sex.

• Medications: As many as 25% of all cases of ED are due to medication side effects. Several types of drugs can cause ED by interfering with nerve impulses or blood flow to the penis. They include antidepressants such as amitriptyline (Elavil®), fluoxetine (Prozac®), paroxetine (Paxil®), and sertraline (Zoloft®); stimulants such as mixed amphetamine (Adderall®) and cocaine; antihistamines such as diphenhydramine (Benadryl®) and fexofenadine (Allegra®); medications to treat high blood pressure such as propranolol (Inderal®) and clonidine (Catapres®), heart medications such as digoxin (Lanoxin®); antiulcer drugs such as cimetidine (Tagamet®); pain medicines such as opiates (methadone, codeine, morphine, oxycodone); and prostate cancer drugs such as finasteride (Proscar®). Tranquilizers such as diazepam (Valium®) and alprazolam (Xanax®) and sleeping aids such as temazepam (Restoril®) and zolpidem (Ambien®) may also cause ED.

• Substance abuse: Heavy or chronic (long-term) use of alcohol, marijuana, heroin, cocaine, methamphetamine, or other drugs often causes ED and decreased sexual drive.

Signs and Symptoms

• Symptoms associated with erectile dysfunction (ED) include the occasional inability to obtain a full erection, inability to maintain an erection throughout intercourse, and complete inability to achieve an erection. Lack of morning erections are also seen along with a decrease in sex drive (libido).

Diagnosis

• It is normal to experience ED on occasion. But if ED lasts longer than two months or is a recurring problem, doctors recommend a physical exam. Although ED might be seen as a personal or embarrassing problem, it is important for patients to seek treatment, which is successful in many cases.

• History and physical examination: A medical history includes the frequency and duration of symptoms, the presence or absence of morning erections, and the quality of the relationship with the sexual partner. The sudden onset of erectile dysfunction (ED) in association with normal morning erections suggests ED caused by psychological issues, such as anxiety disorders.

• Psychological examination: 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. Questions about how and when the condition developed, any medications taken, and any other physical conditions or diseases are included. A patient's doctor will also want to discuss recent physical or emotional changes.

• The medical history may reveal that the disorder is due to a chronic disease such as atherosclerosis (hardening of the arteries), hypertension (high blood pressure), or diabetes. A review of all medications, including over-the-counter (OTC), prescription drugs, and dietary supplements is also important.

• The doctor will look for signs of hypogonadism (lack of male hormone production), such as gynecomastia (increase in breast size) or the loss of axillary (arm pit) and pubic hair. The genital examination includes an evaluation of the size and consistency of the testes. The penis should be examined for any fibrosis (scar tissue) indicative of Peyronie's disease, an inflammatory condition causing scar tissue formation in the penis.

• Duplex ultrasound: Duplex ultrasound is used to evaluate blood flow, venous leak, signs of atherosclerosis (hardening of the arteries), and scarring or calcification of erectile tissue. Erection is induced by injecting prostaglandin (alprostadil or Caverject®, Edex®), a hormone-like stimulator of erection produced in the body. Ultrasound is then used to see vascular dilation and measure penile blood pressure (which may also be measured with a special cuff). Measurements are compared to those taken when the penis is flaccid.

• Prostate examination: An enlarged prostate, which can be detected with a digital rectal examination (DRE), can interfere with blood flow and nerve impulses in the penis, leading to ED.

• Penile nerve function: In the bulbocavernosus reflex test, the head of the penis (glans) is squeezed while observing for contraction of the external anal sphincter. This is visualized or felt during a digital rectal examination. This test is used to determine if there is sufficient nerve sensation in the penis.

• Nocturnal penile tumescence (NPT): It is normal for a man to have five to six erections during sleep, especially during rapid eye movement (REM). These erections occur about every 90 minutes and last for about 30 minutes. Their absence may indicate a problem with nerve function or blood supply in the penis. NPT is determined by using snap gauge, which involves wrapping three plastic bands of varying strength around the penis (performed in a sleep lab). Erectile function is assessed according to which bands break. Strain gauge involves placing special elastic bands at the base and tip of the penis. These bands stretch during erection and register changes in circumference.

• Penile biothesiometry: This test uses electromagnetic vibration to evaluate sensitivity and nerve function in the penis. A decreased perception of vibration may indicate nerve damage in the pelvic area, which can lead to ED.

• Dynamic infusion cavernosometry and cavernosography (DICC): DICC is a procedure that involves four phases to evaluate the flow of blood and pressure functions of the penis. Fluid is pumped into the penis at a predetermined rate. By measuring the rate at which fluid must be pumped to attain a rigid erection, doctors can determine the severity of the venous leak. Also, a dye is injected into the artery in the penis believed to be damaged and X-rays are taken.The test assesses the integrity of the arterial and venous circulatory systems of the penis during an erection. DICC is invasive, requiring two needles to remain in the penis for saline infusion and pressure recording. Local anesthesia and an intracavernosal (into the penis) injection of a vasoactive drug are given prior to initiation. Vasoactive drugs, such as phentolamine (Regitine®), cause erection by dilating blood vessels in erectile tissue. Normally, these injections produce an erection lasting about 20 minutes. DICC has primarily been reserved for individuals considering the option of vein ligation (surgically tying off) with or without arterial bypass.

• Arteriography: This test is given to individuals who are candidates for vascular reconstructive surgery (blood vessel reconstruction).

• Blood tests: Blood tests can indicate conditions that may interfere with normal erectile function. These tests measure anemia (low levels of red blood cells), cholesterol (total cholesterol, low density lipoprotein or LDL, and triglycerides), blood sugar, liver, prostate, and kidney function, and thyroid function (regulates production of sex hormones). Hormone levels (testosterone and prolactin) are also checked, as excess prolactin (hyperprolactinemea) can lower testosterone levels, which can diminish libido (sex drive).

Complications

• Psychological problems may exist along with ED, such as depression, stress, and anxiety. PTSD, or post traumatic stress disorder, is a type of anxiety that can occur in individuals after traumatic events such as sexual abuse, physical assault, witnessing a death, the unexpected death of a loved one, or natural disaster. PTSD can contribute to ED.

• Because sexual performance is often a big part of a man's self-esteem, experiencing erectile dysfunction (ED) can be devastating not only to a man's sex life, but to his emotional outlook also. ED can cause men to feel inadequate in their sexual role with their mate. Men who are suffering from ED tend to isolate themselves from their relationships and withdraw from their partners. The psychological effects of ED can invade every aspect of a man's life, from his relationship with his partner, to his interactions on a social level, to his job performance. Therefore, it is important for a man who is suffering from ED to feel as comfortable as possible discussing his condition with his partner, and with his physician, in order to discover the treatment strategy that can best help overcome this condition.

Treatment

• A wide variety of options exist for treating erectile dysfunction (ED). Treatments include psychological counseling, medications, mechanical devices, and surgery. The cause and severity of the ED are important factors in determining the best treatment or combination of treatments for the individual. If ED is the result of a medical condition, the cost of treatment may be covered by insurance.

• Psychological counseling: Psychological counseling can help with ED that is caused by stress, anxiety, or depression. ED can also cause these issues. The individual and their partner may be instructed to visit a sex therapist, psychologist, or psychiatrist with experience in treating sexual problems. Qualified therapists work with couples to reduce tension, improve sexual communication, and create realistic expectations for sex, all of which can improve symptoms of ED. Therapists also help the individual work through issues such as sexual abuse as a child. Psychological therapy may be effective along with medical or surgical treatment. However, medical and surgical treatment may not help someone with ED who is suffering from psychological causes.

• Oral medications: Oral medications available to treat ED include sildenafil (Viagra®), tadalafil (Cialis®), and vardenafil (Levitra®). The U.S. Food and Drug Administration (FDA) approved Viagra® in 1998, and it became the first oral medication for ED on the market. Since then, Levitra® and Cialis® have been approved, providing more options for oral therapy. These drugs are chemically known as phosphodiesterase-5 inhibitors (PDE-5). They enhance the effects of nitric oxide, a chemical messenger that relaxes smooth muscles in the penis. This increases the amount of blood flowing into the penis and allows an erection in response to sexual arousal and stimulation. These medications do not automatically produce an erection. Instead they allow an erection to occur after physical and psychological stimulation and arousal. Many men experience improvement in erectile function after taking these medications regardless of the cause of their impotence.

• Generally, these medications are absorbed and processed rapidly by the body and are usually taken 30 minutes to one hour before intercourse. Cialis® has been reported in clinical trials to stay in the body longer than the others. It promotes erection within 30 minutes and enhances the ability to achieve erection for up to 36 hours.

• Common side effects of phosphodiesterase inhibitors include headache, reddening of the face and neck (flushing), indigestion, and nasal congestion. Cialis® may cause muscle aches and back pain, which usually go away on their own within 48 hours.

• Medications prescribed for the treatment of erectile dysfunction may cause significant side effects when mixed with certain heart drugs called nitrates, including nitroglycerin (Nitrostat®, Nitro-Bid®), isosorbide mononitrate (Imdur®), and isosorbide dinitrate (Isordil®). Nitrates are often prescribed to reduce chest pain, dilate the blood vessels, and lower blood pressure. Because ED medications also reduce blood pressure, combining these two types of medication can cause a dangerous drop in blood pressure. Experts do not recommend taking sildenafil (Viagra®), vardenafil (Levitra®), or tadalafil (Cialis®) if nitrates are used. If an individual has coronary heart disease (CHD) or has had a heart attack in recent months, be sure to check with a doctor before taking any of these drugs for erectile dysfunction. These drugs should also not be used along with alpha blockers.

• Prostaglandin E1 (alprostadil): Two treatments involve using a drug called alprostadil (Muse®, Caverject®, Edex®). Alprostadil is a synthetic version of the hormone prostaglandin E1. This hormone helps relax smooth muscle tissue in the penis (corpus cavernosum), which enhances the blood flow needed for an erection. There are two ways to use alprostadil, including needle-injection therapy and intraurethral (into the urethra) therapy. With needle-injection, a needle is used to inject alprostadil (Caverject®, Edex®) into the base or side of the penis, performed at a doctor's office or hospital. This generally produces an erection in five to 20 minutes that lasts for 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. It should not be used more than three times per week, and there must be at least 24 hours (one day) between each dose. The cost per injection can be expensive. Injecting a mixture of alprostadil and other prescribed drugs (including papaverine and phentolamine) may be a less expensive and more effective option. A risk of infection exists at the injection site, especially in immunocompromised individuals such as those with human immunodeficiency virus (HIV). Healthcare professionals recommend using care to protect the individual using Caverject® and their sexual partner, as blood from the injection site after could be a carrier of sexually transmitted diseases, such as HIV or hepatitis.

• Medicated Urethral System for Erection (Muse®) is a self-administered intraurethral (into the urethra or opening in penis) therapy. It involves using a disposable applicator to insert a tiny suppository, about half the size of a grain of rice, into the tip of the penis. The suppository, placed about two inches into the urethra, is absorbed by erectile tissue in the penis, increasing the blood flow and causing an erection. Although needles are not involved, this method may be painful or uncomfortable. Side effects may include pain, minor bleeding in the urethra, dizziness, and formation of fibrous (scar) tissue. Again, bleeding may occur during the use of this drug, so care should be taken by the individual using Muse® to protect themselves and their sexual partner.

• Hormone replacement therapy: For the small number of men who have testosterone deficiency, testosterone replacement therapy may be an option. While it is fairly well established that testosterone plays a role in libido (sexual desire), its role in ED remains unclear. ED occurs in men with normal or moderately low levels of testosterone, so it cannot be concluded that testosterone is the primary modulator of erectile function. However, among men diagnosed with hypogonadism, a condition characterized by abnormally low testosterone, erections do improve after testosterone replacement. For these men with ED, testosterone therapy is recommended to restore erectile function.

• Testosterone replacement therapy has also been recommended as a second-line approach to treatment of ED when prescription medications alone have failed and when prostate cancer has been ruled out. However, testosterone may increase the growth of prostate cancer and is not used in individuals with this disease or an enlarged prostate (benign prostatic hyperplasia or BPH).

• Yohimbine: Yohimbine comes from the bark of the Pausinystalia yohimbe tree. Yohimbine hydrochloride is a standardized form of yohimbine that is available as a prescription drug in the United States, and has been reported in human studies to be effective in the treatment of male impotence. Yohimbine hydrochloride (HCL) has also been used for the treatment of sexual side effects caused by some antidepressants (selective serotonin reuptake inhibitors), female hyposexual (low sexual desire) disorder, as a blood pressure boosting agent, and xerostomia (dry mouth due to lack of saliva).Yohimbine HCL improves erections for 10-20% of men. It stimulates the parasympathetic nervous system, which is linked to erection, and may increase libido (sexual desire). It is necessary to take the medication for six to eight weeks before determining whether it will work or not. Yohimbine HCL has a stimulatory effect and side effects include elevated heart rate and blood pressure, mild dizziness, nervousness, and irritability.

• Vacuum devices: This treatment involves the use of an external vacuum and one or more rubber bands (tension rings). To begin, a hollow plastic tube is placed over the penis. This tube is available by prescription or through various vendors. Then a hand pump is used to create a vacuum in the tube that pulls blood into the penis. Once an adequate erection is achieved (usually one to three minutes), a tension ring is slipped around the base of the penis to maintain the erection. The vacuum device is then removed. The erection typically lasts long enough for a couple to have sexual intercourse. The ring can be left in place for 25 to 30 minutes. The tension ring is removed 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 such as atherosclerosis (hardening of the arteries) or tumors. The goal of this treatment is to correct a blockage of blood flow to the penis so that erections can occur naturally; however, long-term success of this surgery is unclear. Complications are minimal and include abdominal or scrotal pain/swelling and occasional temporary numbness on the top surface of the penis. Abstinence from sexual activity involving the erect penis is recommended for the first six weeks after the operation.

• 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. These implants consist of either an inflatable device or semi-rigid 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. Penile implants are also sometimes used to treat Peyronie's disease, a disorder that causes bent or painful erections. As with any surgery, there is a risk of complications such as infection. Most men go home within 24 hours of surgery. Although new penile implant designs are very reliable and may last a lifetime, they can malfunction. For example, in some semi-rigid devices, internal parts can break down over time, leading to a prosthesis malfunction. In inflatable devices, fluid can leak or the valve or pump device can fail. Surgery is necessary to repair or replace a broken implant. Penile implants do not usually affect urination, sex drive, orgasm, or ejaculation.

• A consideration before implanting a device into the penis is that implants cause an erection, but they do not increase sexual desire or sensation. A penile implant will be shorter than the natural erection. Some partners feel that sexual pleasure is diminished by their lack of involvement in creating an erection. This surgery is permanent. If the implant is removed, the patient will not be able to get an erection. There may be reduced sensation in the head of the penis. In some men, this improves when they also take phosphodiesterase type 5 inhibitors, such as sildenafil (Viagra®), tadalafil (Cialis®), and vardenafil (Levitra®).

Integrative Therapies

• Unclear or conflicting scientific evidence:

• Acupressure, shiatsu: Results from preliminary study suggest a benefit of vaginal acupressure/pelvic massage in the treatment of sexual dysfunction. Additional studies are needed.

• With proper training, acupressure appears to be safe if self-administered or administered by an experienced therapist. Serious long-term complications have not been reported, according to scientific data. Hand nerve injury and herpes zoster ("shingles") cases have been reported after shiatsu massage. Forceful acupressure may cause bruising.

• Acupuncture: The practice of acupuncture originated in China 5,000 years ago. Today it is widely used throughout the world and is one of the main pillars of Chinese medicine. It involves the insertion of needles in various point of the body to help move the "chi" or energy. A few clinical studies have suggested that acupuncture may help individuals suffering from erectile dysfunction (ED). The results found that acupuncture can be an effective treatment option in more than two-thirds of patients with ED caused by psychological factors including stress, anxiety, and depression.

• Needles must be sterile in order to avoid disease transmission. Avoid with valvular heart disease, medical conditions of unknown origins, or infections. Acupuncture should not be applied to the chest in patients with lung diseases or on any area that may rely on muscle tone to provide stability. Avoid use in infants, young children, or in patients with needle phobias. Use cautiously with bleeding disorders, neurological disorders, seizure disorders, or diabetes. Use cautiously in elderly or medically compromised patients. Use cautiously in patients who will drive or operate heavy machinery after acupuncture. Use cautiously if taking anticoagulants. Avoid if pregnant.

• Arginine: L-arginine, or arginine, is considered a semi-essential amino acid, because although it is normally synthesized in sufficient amounts by the body, supplementation is sometimes required. Early studies found that men with low nitrate levels (a cause of erectile dysfunction) in their blood or urine may find arginine supplements to be useful for managing erectile dysfunction. A randomized, controlled clinical trial reported improvements in patients with ED following use of a combination of L-arginine, glutamate, and yohimbine hydrochloride. Notably, yohimbine hydrochloride is an U.S. Food and Drug Administration (FDA) approved drug therapy for ED, and the effects caused by arginine alone in this combination therapy are difficult to determine. It is not clear what doses of arginine may be safe or effective in treating this condition, and comparisons have not been made with other agents used for ED. Larger, high-quality studies are needed.

• L-arginine is generally safe in recommended dosages, although drug interactions may be seen, especially with drugs to lower high blood pressure. Avoid if allergic to arginine, or with a history of stroke, or liver or kidney disease. Avoid if pregnant or breastfeeding. Use caution if taking blood-thinning drugs (like warfarin or Coumadin®) and blood pressure drugs or herbs or supplements with similar effects. Blood potassium levels should be monitored. L-arginine may worsen symptoms of sickle cell disease. Caution is advised in patients taking prescription drugs to control sugar levels.

• Clove: A small amount of human research reports that a combination cream with clove and other herbs may be helpful in the treatment of premature ejaculation. However, well-designed studies of the effectiveness of clove alone are needed before a conclusion can be drawn.

• Avoid if allergic to Balsam of Peru, clove, eugenol, or some licorice and tobacco (clove cigarette) products. Avoid with bleeding disorders and in pediatric patients. Avoid use of undiluted clove oil on the skin. Use cautiously with seizure disorders and kidney or liver dysfunction. Avoid if pregnant or breastfeeding.

• Coenzyme Q10: There is early evidence that supports the use of CoQ10 for increasing sperm count and motility in patients with idiopathic asthenozoospermia. Better studies are needed before a conclusion can be made.

• Allergy associated with Coenzyme Q10 supplements has not been documented in the available literature, although rash and itching have been reported rarely. Stop use two weeks before surgery/dental/diagnostic procedures with bleeding risk and do not use immediately after these procedures. Use caution with a history of blood clots, diabetes, high blood pressure, heart attack, or stroke, or with anticoagulants (blood thinners) or antiplatelet drugs (like aspirin, warfarin), or blood pressure, blood sugar, cholesterol, or thyroid drugs. Avoid if pregnant or breastfeeding.

• Coleus: Coleus (Coleus forskohlii) has been used in Asian traditional medicine for over 2,000 years. A component of coleus, called forskolin, was studied in humans in addition to prostaglandin E1, a drug commonly used in erectile dysfunction. Positive effects were seen with forskolin and progstaglandin when the prostaglandin alone did not work for erectile dysfunction.

• Caution is advised when taking coleus supplements, as numerous adverse effects including drug interactions with blood pressure lowering medications are possible. Coleus should not be used if pregnant or breastfeeding, unless otherwise directed by a doctor.

• Cordyceps: Cordyceps sinensis is a fungus found mainly in China, Nepal, and Tibet. There is currently not enough available scientific evidence regarding the use of Cordyceps for sexual dysfunction. High quality clinical research is needed in this area.

• Avoid if allergic or hypersensitive to cordyceps, mold, or fungi. Use cautiously with diabetes, prostate conditions, bleeding disorders, or if taking anticoagulant medications, immunosuppressive medications, or if on hormonal replacement therapy or oral contraceptives. Avoid with myelogenous-type cancers. Avoid if pregnant or breastfeeding.

• DHEA (dehydroepiandosterone): DHEA is an endogenous hormone (made in the human body) secreted by the adrenal gland. DHEA serves as forerunner to male sex hormones (androgens) and female sex hormones (estrogens). DHEA levels in the body begin to decrease after age 30. Although some human studies report positive benefits on erectile dysfunction and sexual function while using DHEA in both men and women, better research is necessary before a clear conclusion can be drawn. Preliminary evidence suggests that DHEA may offer some benefit for increasing libido in premenopausal women. Well designed clinical trials are required before recommendations can be made.

• Caution is advised when taking DHEA supplements, as numerous adverse effects including drug interactions are possible.

• Ephedra: Early small studies suggest that ephedra may increase sexual arousal in women. Further well-designed research is needed to confirm these results.

• The U.S. Food and Drug Administration (FDA) has collected more than 800 reports of serious toxicity, including more than 22 deaths from the use of ephedra and/or ephedra containing products. Avoid use in individuals younger than 18 years old. Avoid use for prolonged periods (longer than seven days) due to risk of abuse or toxicity. Discontinue use at least one week prior to major surgery or diagnostic procedures. Use cautiously with cardiovascular disease, including structural heart disease, arrhythmia, coronary artery disease, high blood pressure, cerebrovascular disease, and a history of stroke or transient ischemic attack. Use cautiously with depression, anxiety disorders, anorexia/bulimia, a history of suicidal ideation, insomnia, tremors, urinary retention, enlarged prostate, diabetes, kidney disease, glaucoma, thyroid disease, and peptic ulcer disease. Use cautiously with monoamine oxidase inhibitor (MAOI) or stimulant use. Avoid if pregnant or breastfeeding.

• Ginkgo: Ginkgo (Ginkgo biloba) has been used medicinally for thousands of years, and is one of the top selling herbs in the United States. Ginkgo is commonly used for decreased blood flow. Ginkgo has been reported in animal and human models as having vascular (blood vessel) relaxant properties, which may act on corpus cavernosum tissue of the penis and improve penile blood flow in patients with ED. Ginkgo has also been reported to be effective in treating antidepressant-induced decreased libido and erectile dysfunction.

• Ginkgo may increase the chances of bleeding in sensitive individuals, such as those taking blood thinning drugs like warfarin (Coumadin®). Avoid if allergic or hypersensitive to members of the Ginkgoaceaefamily. If allergic to mango rind, poison sumac, poison ivy, poison oak, or cashews, then allergy to ginkgo is possible. Ginkgo should be stopped two to three weeks before surgical procedures. Use cautiously with seizures or in children. Ginkgo seeds are dangerous and should be avoided. Skin irritation and itching may also occur due to ginkgo allergies. Do not use ginkgo in supplemental doses if pregnant or breastfeeding.

• Ginseng: Asian ginseng, or Panax ginseng, has been used for more than 2,000 years in Chinese medicine for various health conditions. Preliminary evidence indicates that ginseng may be effective in improving the signs and symptoms of erectile dysfunction (ED). Early studies suggest that applying an herbal combination containing Panax ginseng on the penis may help treat premature ejaculation. However, because ginseng was tested with other herbs, its individual effects on sexual function and libido are unclear. Early studies also suggest that a product containing Panax ginseng, L-arginine, Ginkgo biloba, damiana, and multivitamin/minerals may improve sexual arousal in women with decreased sex drives and menopausal women. Studies with Panax ginseng alone are needed before strong conclusions can be made.

• Avoid ginseng with known allergy to plants in the Araliaceae family. There has been a report of a serious life-threatening skin reaction, possibly caused by contaminants in ginseng formulations.

• Horny goat weed: Horny goat weed has been traditionally used to increase fertility. Early study suggests that horny goat weed may be of benefit for sexual dysfunction in renal failure patients. Additional study is needed in this area.

• Avoid if allergic/hypersensitive to horny goat weed (Epimedium grandiflorum), its constituents, or related plants in the Berberidaceae family. Use cautiously with tachyarrhythmia, decreased blood pressure, frequent nosebleeds, musculoskeletal disorders, bipolar disorder, immune function disorders, homocysteine disorders, hypothyroid conditions, and cardiovascular disease. Use cautiously if taking anticoagulant or antiplatelet (blood thinning) medications, antihypertensive (blood pressure) medications, antidepressants (MAOIs), interleukins, or cholesterol-lowering medications. Avoid with hormone-sensitive conditions or if taking estrogen or oral contraception. According to traditional Chinese medicine (TCM), avoid in patients with "fire from yin deficiency" (people with too much "yang" or heat, masculinity, and activity, based on Chinese philosophy). Avoid if pregnant or breastfeeding.

• Hypnotherapy, hypnosis: There is inconclusive evidence from preliminary research on the use of hypnotherapy for erectile dysfunction. Additional study is needed before a firm conclusion can be drawn.

• Use cautiously with mental illnesses like psychosis/schizophrenia, manic depression, multiple personality disorder or dissociative disorders. Use cautiously with seizure disorders.

• L-carnitine: L-carnitine, carnitine, or acetyl-L-carnitine, is an amino acid (building block for proteins). High concentrations of carnitine are found in muscle tissue. Preliminary studies suggest that addition of acetyl-L-carnitine (in combination with propionyl-L-carnitine, another form of carnitine) helped sildenafil (Viagra®) work better for patients with erectile dysfunction (ED). However, more rigorous trials should be performed.

• Caution is advised when taking L-carnitine supplements, as adverse effects including drug interactions are possible. Avoid with known allergy or hypersensitivity to carnitine. Use cautiously with peripheral vascular disease, hypertension (high blood pressure), alcohol-induced liver cirrhosis, and diabetes. Use cautiously in low birth weight infants and individuals on hemodialysis. Use cautiously if taking anticoagulants (blood thinners), beta-blockers, or calcium channel blockers. Avoid if pregnant or breastfeeding.

• Maca: Maca (Lepidium meyenii) is a vegetable that has been cultivated as a root crop for at least 2,000 years. It can be found wild in Peru, Bolivia, Paraguay, and Argentina, but has primarily been cultivated in the highlands of the Peruvian Andes. Traditionally in Peru, maca has been used as a male aphrodisiac to increase sexual desire. Maca may improve sexual desire in healthy men independent of changes in mood, or serum testosterone (male hormone), and estradiol (female hormone) levels. Higher quality studies are needed in this area, in both men and women.

• Avoid if allergic/hypersensitive to maca (Lepidium meyenii), any of its constituents, or other members of the Brassicaceae family, formerly Cruciferae (broccoli, brussel sprouts, cabbage, or cauliflower). Use cautiously with anticoagulation therapy, hypertension, hormone responsive cancers such as breast cancer, or prostate cancer, and if using oral contraceptives or stimulants. Avoid if pregnant or breastfeeding.

• Muira puama: Muira puama (Ptychopetalum olacoides) has been used historically for enhancement of libido and as a treatment for erectile dysfunction by Brazilian native people. Well-designed human trials of muira puama, as well as safety data, are necessary. Additional study is also needed regarding the use of muira puama for female sexual dysfunction.

• Use cautiously with steroidal drug therapy, hormone-sensitive conditions (breast cancer, endometriosis, ovarian cancer, prostate cancer), high blood pressure, or heart disease. Use cautiously if taking medications acting on the central nervous system (CNS). Avoid if allergic/hypersensitive to muira puama (Ptychopetalum olacoides), any of its components or any related members of the Olacaeae family. Avoid if pregnant or breastfeeding.

• Pomegranate: Pomegranate juice has been studied in the treatment of mild to moderate erectile dysfunction. Early study is unclear, and more studies are needed to make a firm conclusion.

• Avoid if allergic or hypersensitive to pomegranate. Avoid with diarrhea or high or low blood pressure. Avoid taking pomegranate fruit husk with oil or fats to treat parasites. Pomegranate root/stem bark should only be used under supervision of a qualified healthcare professional. Use cautiously with liver damage or disease. Pomegranate supplementation can be unsafe during pregnancy when taken by mouth. The bark, root and fruit rind can cause menstruation or uterine contractions. Avoid if breastfeeding due to a lack of scientific data.

• Psychotherapy: Individual, couples, or group psychotherapy may be helpful for men with erectile dysfunction. However, prescription medication may be needed to alleviate symptoms.

• Psychotherapy cannot always fix mental or emotional conditions. Psychiatric drugs are sometimes needed. In some cases symptoms may worsen if the proper medication is not taken. Not all therapists are qualified to work with all problems. Use cautiously with serious mental illness or some medical conditions because some forms of psychotherapy may stir up strong emotional feelings and expression.

• Pycnogenol: Pycnogenol® is the patented trade name for a water extract of the bark of the French maritime pine (Pinus pinaster ssp. atlantica), which is grown in coastal south-west France. Pycnogenol® has protective effect on blood vessels. Pycnogenol®, in combination with L-arginine, may cause an improvement in sexual function in men with erectile dysfunction (ED). It is not known what effect each of the individual compounds may have directly on this condition. Further research is needed.

• Caution is advised when taking Pycnogenol®, as it may increase the chances of bleeding in sensitive individuals, such as those taking blood thinning drugs like warfarin (Coumadin®). Avoid if allergic/hypersensitive to pycnogenol, its components, or members of the Pinaceae family. Avoid if pregnant or breastfeeding.

• Yoga: Yoga is an ancient system of relaxation, exercise, and healing with origins in Indian philosophy. There is early evidence to support the use of yoga in the treatment of delayed ejaculation in males. Larger well designed and controlled trials are needed to further assess the effects of yoga for sexual health.

• Yoga is generally considered to be safe in healthy individuals when practiced appropriately. Avoid some inverted poses with disc disease of the spine, fragile or atherosclerotic neck arteries, extremely high or low blood pressure, glaucoma, detachment of the retina, ear problems, severe osteoporosis, cervical spondylitis, or if at risk for blood clots. Certain yoga breathing techniques should be avoided with heart or lung disease. Use cautiously with a history of psychotic disorders. Yoga techniques are believed to be safe during pregnancy and breastfeeding when practiced under the guidance of expert instruction. However, poses that put pressure on the uterus, such as abdominal twists, should be avoided in pregnancy.

• Yohimbe bark extract: Yohimbine hydrochloride is a prescription drug that has been shown in multiple human trials to effectively treat erectile dysfunction. Yohimbine hydrochloride has also been suggested to treat sexual side effects of selective serotonin reuptake inhibitor (SSRI) antidepressants. However, although yohimbine is present in yohimbe bark extract, levels are variable and often very low. Yohimbine has also been proposed to increase female libido. More study is needed in these areas before a conclusion can be made.

• Yohimbine is generally well tolerated in recommended doses. However, many side effects have been reported with yohimbine hydrochloride and may apply to yohimbe bark. Avoid if allergic to yohimbe, any of its components, or yohimbine-containing products. Use cautiously with peptic ulcer disease, kidney disease, high blood pressure, heart disease or if taking drugs that affect blood sugar levels. Avoid with benign prostate hypertrophy (enlarged prostate), anxiety, mania, depression, stress disorders, post-traumatic stress disorders, bipolar disorders, or schizophrenia. Avoid use in children or if pregnant or breastfeeding.

• Fair negative scientific evidence:

• Deer velvet: Deer velvet has a reputation as an aphrodisiac that may improve sexual energy by potentially strengthening and balancing the body and restoring overall energy. Traditionally, the tip and upper portions of the antler are considered to have the greatest medicinal value. The first published human trial to investigate these claims yielded no statistically significant effects on sexual functioning in mid-life men. However, the authors noted that these results reflected the average effect; they mentioned that some participants reported feeling benefits, although positive responses were not consistent. In addition, the quality of deer velvet products may vary considerably. Additional research is needed to determine the effect of deer velvet on sexual function, libido, and erectile dysfunction.

• Use cautiously in patients in whom an androgenic effect is contraindicated. However, deer velvet has not been shown to change male hormone levels or sexual behavior. Use cautiously in patients in whom supplemental estradiol and/or progesterone is contraindicated. Use cautiously in patients taking hepatotoxic agents. Use cautiously in patients taking sexual enhancing agents. Use cautiously in patients taking energy enhancing or muscle strengthening agents. Avoid in pregnant and lactating women.

Prevention

• A simple way to improve erectile dysfunction (ED) is to introduce lifestyle changes. For some men, adopting a healthier lifestyle by quitting smoking, exercising regularly, and/or reducing stress may be all that is needed to find relief. For others, adopting these lifestyle changes in addition to other treatments, such as medicines or surgery, can further help. Some tips on preventing symptoms of ED include limiting or avoiding the use of alcohol and other recreational drugs (marijuana, cocaine), quitting smoking, exercising regularly (at least 30 minutes daily), reducing stress, getting enough sleep (eight hours a night), dealing with anxiety or depression (through counseling and medication), and seeing a doctor for regular checkups and medical screening tests.

• Although it may be uneasy to talk about, ED is a treatable condition and should be discussed with a healthcare professional.

Author Information

• This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

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