Aging, liver and kidney problems, and concurrent use of certain medications (such as erythromycin [an antibiotic] and protease inhibitors for HIV) slows the metabolism (breakdown) of sildenafil. Slowed breakdown allows sildenafil to accumulate in the body and potentially may increase the risk of side effects. Therefore, in men over 65 years of age, in men with significant kidney and liver disease, and in men who also are taking medications called protease inhibitors, the doctor will initiate sildenafil at a lower dose (25 mg) to avoid accumulation of sildenafil in the body. A protease inhibitor ritonavir (Norvir) is especially potent in increasing the accumulation of sildenafil, thus men who are taking Norvir should not take sildenafil doses higher than 25 mg and at a frequency of no greater than once in 48 hours. Other medications that may affect the level of sildenafil include erythromycin and ketoconazole.

This man’s history is adequate to rule out arterial or venous insufficiency as he can masturbate to produce a rigid, sustainable erection and he responds well to tadalafil. Due to his report of gradual onset, his lack of response to ongoing sexual therapy, and his tremendous anxiety associated with the issue, the decision was made to offer a PCDU to assess for a vascular etiology for his disorder. PCDU revealed normal peak flow bilaterally of 40 cm/sec with no end diastolic flow and 100% rigidity obtained. His erection lasted more than 2 hours and required phenylephrine to resolve the erection.
Mental causes of sexual dysfunction include: depression, stress, anxiety and insomnia.  When one of these conditions leads to ED, usually once the condition is cured normal sexual behavior returns.  If you believe you have one of these conditions, see your doctor for an evaluation before beginning any treatment.  One side effect of antidepressants is erectile dysfunction.
The penis is composed of three cylinders: two on the top, the corpora cavernosa and one on the bottom, the corpus spongiosum. All of these are involved in the process of an erection. The corpora cavernosa are composed of potential spaces that can distend with blood, causing rigidity of the penile shaft. The corpus spongiosum is important for rigidity of the glans of the penis. When aroused, stimulated chemicals are released from the nervous system (nitric oxide is one) that stimulate the arteries to the penis to relax and increase blood flow into the penis. These potential spaces, like a sponge, can expand when more blood flow comes in the penis. Each corpora cavernosa is surrounded by an outer coating the tunica albuginea. When the penis fills with blood, these potential spaces, the sinusoids, compress the veins in the corpora against the side of the tunica albuginea, thus preventing blood from leaving the penis. It is this compression of the veins that allows for the erection to become fully rigid.
Erectile dysfunction may be an unpleasant condition that no one really wants to talk about, failing to acknowledge it won’t make the problem go away. Your best defense against health problems like this is to learn everything you can about it so you can tackle the problem at the root. If you’re ready to stop living in embarrassment about your sexual function, become an advocate for yourself and your own health and talk to your doctor.
Is your erectile dysfunction due to psychological (stress, relationship problems, etc.) or physical factors? Your doctor may ask if you note erections at night or in the early morning. Men have involuntary erections in the early morning and during REM sleep (a stage in the sleep cycle with rapid eye movements). Men with psychogenic erectile dysfunction (erectile dysfunction due to psychological factors such as stress and anxiety rather than physical factors) usually maintain these involuntary erections. Men with physical causes of erectile dysfunction (for example, atherosclerosis, smoking, and diabetes) usually do not have these involuntary erections. Men with psychogenic erectile dysfunction may relate the onset of problems to a "stressor," such as failed relationship. Your doctor may suggest a test to determine if you have erections during sleep, which may suggest that there may be a psychological cause of the erectile dysfunction.
Erectile dysfunction is more common than most people think. About 40% of men will notice some degree of problem by age 40. The aging of the penis can begin as early as the late 20s but becomes severe enough to notice typically starting in the 40s. As men get older, their odds of getting erectile dysfunction increases by about 10% per decade, and the severity of the problem also increases.
Performance anxiety can be another cause of impotence. If a person wasn’t able to achieve an erection in the past, he may fear he won’t be able to achieve an erection in the future. A person may also find he can’t achieve an erection with a certain partner. Someone with ED related to performance anxiety may be able to have full erections when masturbating or when sleeping, yet he isn’t able to maintain an erection during intercourse.
Alprostadil should not be used in men at higher risk for priapism (erection lasting longer than six hours) including men with sickle cell anemia, thrombocytopenia (low platelet count), polycythemia (increased red blood cell count), multiple myeloma (a cancer of the white blood cells), and is contraindicated in men prone to venous thrombosis (blood clots in the veins) or hyperviscosity syndrome who are at increased risk for priapism.
The common PDE5 inhibitor drugs approved in the United States are sildenafil (Viagra), vardenafil (Levitra and Staxyn, the generic form), tadalafil (Cialis), or avanafil (Stendra). All of the currently approved PDE5 inhibitors work in the same way. They differ in the number of available doses, how quickly they work and last in your system, the dosing, and to some extent in the side effects. However, they generally share the same indications and contraindications. Currently, tadalafil is the only medication that patients can take on a daily basis and is approved for the treatment of both ED and BPH (benign enlargement of the prostate).
Similar to the general population (58), in subjects consulting for sexual dysfunction, T deficiency is progressively more prevalent as a function of age (50). In a series of 4,890 subjects consulting our Sexual Medicine and Andrology Unit for sexual dysfunction, one in five (19.6%) and one in three (29.4%) patients have total T below 10.4 and 12 nmol/L, respectively (60). Clinical correlates of T deficiency show different figures according to patient’s age. In fact, we previously demonstrated that in the youngest quartile (17–42 years old), but not in the oldest one (62–88 years old), severity of reported ED and penile blood flow impairment (dynamic peak systolic velocity) were not associated to decreasing testosterone levels (50). It is possible to speculate that, in young individuals, intercourse-related penile erection is such a complex phenomenon that other determinants (i.e., intrapsychic or relational) might mask its androgen regulation and that T deficiency produces greater sexual disturbances in subjects with greater frailty, such as older individuals. However, reported frequency of spontaneous erection and sexual thoughts were significantly decreased as a function of T decline even in younger subjects (50). Moreover, in young individuals low T was associated with a worse metabolic profile, including hypertriglyceridemia and increased waist circumference (50). Accordingly, the prevalence of MetS in the youngest quartile was clearly associated with T deficiency, as it was in the older quartiles (50). Therefore, T deficiency must be accurately verified in all subjects consulting for sexual dysfunction, even in the youngest ones.
Yet another common erectile dysfunction treatment that can be used in combination with oral drugs is a vacuum pump. This device consists of a plastic cylinder, a pump, a set of constriction bands, and a water-soluble lubricant. The lubricant is applied to the base of the penis to help form an airtight seal. The cylinder is placed over the flaccid penis and held tight against the pelvis. The pump is used to create a vacuum within the cylinder, drawing blood into the penis. Once the penis is engorged with blood, a constriction band is rolled off the cylinder to near the base of the penis. The constriction band is helpful for men with venous leakage, in which blood flows out of the penis as fast as it flows in. However, it should be left on for no more than 30 minutes at a time.
In addition to these laboratory tests, your doctor may also ask you to complete a self-report to gauge your level of sexual function. You’ll be asked questions about your sexual desire (libido), your ability to achieve and maintain an erection, your ability to reach orgasm, your satisfaction level with intercourse, as well as your overall sexual satisfaction. Depending on your answers, and the results of your laboratory tests, your doctor may recommend a psychological evaluation to further explore the potential cause for your ED.

Burnett, whose lab has studied penile erection since the early 1990s, continues, "the insight here is tremendous because it speaks to fundamental biological and vascular" mechanisms of diabetes. "This paper gets back to the physiological relevance of hyperglycemia and how it affects erection.  We show here -- using erection as a model -- the vascular damage caused by diabetes and provide insights into vascular disease beyond this dysfunction," he adds.
The common PDE5 inhibitor drugs approved in the United States are sildenafil (Viagra), vardenafil (Levitra and Staxyn, the generic form), tadalafil (Cialis), or avanafil (Stendra). All of the currently approved PDE5 inhibitors work in the same way. They differ in the number of available doses, how quickly they work and last in your system, the dosing, and to some extent in the side effects. However, they generally share the same indications and contraindications. Currently, tadalafil is the only medication that patients can take on a daily basis and is approved for the treatment of both ED and BPH (benign enlargement of the prostate).

If the patient reports a history of trauma to the genitals that preceded his erectile dysfunction, further evaluation with pharmacologic injection and penile color duplex ultrasound (PCDU) would be indicated to assess for arterial insufficiency or venous occlusive dysfunction (19). Prior to PCDU, however, you might give him a trial of oral PDE5 inhibitors. If those medications are effective, you have effectively ruled out significant arterial insufficiency or venous leakage disease as an etiology. Regardless of outcome of PCDU, no surgical intervention would likely be offered to this man who responds well to oral agents.
The penis contains three cylinders, the two corpora cavernosa, which are on the top of the penis (see figure 1 below). These two cylinders are involved in erections. The third cylinder contains the urethra, the tube that the urine and ejaculate passes through, runs along the underside of the penis. The corpus spongiosum surrounds the urethra. Spongy tissue that has muscles, fibrous tissues, veins, and arteries within it makes up the corpora cavernosa. The inside of the corpora cavernosa is like a sponge, with potential spaces that can fill with blood and distend (known as sinusoids). A layer of tissue that is like Saran Wrap, called the tunica albuginea, surrounds the corpora. Veins located just under the tunica albuginea drain blood out of the penis.
Ganio, M. S., Armstrong, L. E., Casa, D. J., & McDermott, B. P. (2011, November 28). Mild dehydration impairs cognitive performance and mood of men [Abstract]. British Journal of Nutrition, 106(10), 1535–1543. https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/mild-dehydration-impairs-cognitive-performance-and-mood-of-men/3388AB36B8DF73E844C9AD19271A75BF#
Penile prostheses are very effective, and most patients who have a prosthesis placed are satisfied with the prosthesis. However, placement of a prosthesis causes scarring of the tissue within the corpora cavernosa, and if the prosthesis requires removal, other forms of therapy, except for the vacuum device, are often not effective. Thus, most physicians reserve placement of a prosthesis for men who have tried and failed or have contraindications to other therapies.
Psychological causes are less common than we thought but more often the cause in younger men. Performance anxiety triggers the release of adrenaline. Adrenaline causes blood to flow TO the vital organs, such as the heart, lungs and brain, and AWAY from less vital structures like the fingers, toes and the penis. Our bodies do this to cope with the physical stress of a physical attack or physical challenge, but sexual anxiety also triggers this reflex.
There have been rare reports of priapism (prolonged and painful erections lasting more than six hours) with the use of PDE5 inhibitors such as sildenafil, vardenafil, and tadalafil. Patients with blood cell diseases such as sickle cell anemia, leukemia, and multiple myeloma have higher than normal risks of developing priapism. Untreated priapism can cause injury to the penis and lead to permanent impotence. Therefore, if your erection lasts four hours, you should seek emergency medical care.
Erectile dysfunction is a common problem for more than half of men with diabetes. Musicki says that an estimated "50 percent to 75 percent of diabetic men have erectile dysfunction to some degree, [a rate] about threefold higher than in non-diabetic men."  This is not the same type of erectile dysfunction seen in non-diabetics, and it is less effectively treated with conventional drugs like Viagra. 

Erectile dysfunction, also known as ED or impotence, is the inability to attain or maintain an erection of the penis adequate for the sexual satisfaction of both partners. It can be devastating to the self-esteem of a man and of his partner. As many as 30 million American men are afflicted on a continuing basis, and transient episodes affect nearly all adult males. But nearly all men who seek treatment find some measure of relief.
Pornography addiction or dependence is a potential cause for ED that many men fail to consider. If you spend a great deal of time watching and masturbating to pornography, it could cause you to develop unrealistic expectations about sex or about your sexual partners. When this happens, your brain becomes “trained” to not only expect but, in a way, to need that kind of experience in order to achieve arousal and climax. Researchers have actually studied this effect and have given the condition its own name – pornography-induced erectile dysfunction (PIED).
L-arginine is an amino acid that occurs naturally in the human body and helps make that magic nitric oxide so important for supporting an erection. A 1999 study observed the effects of six weeks of L-arginine administered daily among men with ED. One third of those who took five grams per day of L-arginine experienced significant improvements in sexual function.
When these drugs don't work, there are other options. Medications that dilate blood vessels, such as alprostadil, can be injected or deposited in the penis; they work in more than 80 percent of men with diabetes. Beyond that, penile implants can be an effective surgical solution. Implants are either malleable rods, which can be manually adjusted to the desired position, or inflatable cylinders that fill with fluid when a pump under the skin of the scrotum is pressed.
Obesity.  Obesity and erectile dysfunction in men has unfortunately become an epidemic in this country, affecting children, teenagers, young adults and up.  This disease tends to follow men and women through adulthood, if not addressed.  Obesity leads to heart disease, diabetes and high blood pressure.  This trifecta results in the three main medical causes of erectile dysfunction.
Having your current medication checked – if you are taking medication already, it could be that your erection problems are a side effect. Have a doctor check whether this is the cause of your problems and if it is, you might be able to switch medications and then find that your erectile dysfunction goes away completely – or at least improves. Medications that can cause erection problems include:

The U.S. FDA (Food and Drug Administration) has a list of 29 OTC products that claim to treat erectile dysfunction. Patients should avoid these because many contain harmful ingredients. Other natural or herbal remedies such as DHEA, L-arginine, ginseng, and yohimbe are supplements that have been used but have not been proven safe and effective according to some researchers. Before using such compounds, individuals should consult their doctor. According to some experts, acupuncture does not effectively treat erectile dysfunction. Other home remedies for reducing ED symptoms include diet changes such as eating blueberries and citrus fruits and drinking red wine.
Erectile dysfunction is when a man either can’t have an erection or can’t keep an erection long enough to have sex. For only 20% of men with ED, the cause is due to a psychological problem or disorder.2 When the cause of your ED is due to a physical condition, your ED is not a reflection on you or your sexual partner, since lack of arousal isn’t the problem.

With coronary artery disease, a buildup of plaque inside the arteries can limit the amount of blood that’s able to flow through them. If the flow of oxygen-rich blood to your heart muscle is reduced or blocked by this hardening of the arteries, the result can be angina (chest pain) or a heart attack.17 Because the arteries that supply blood to the penis are much smaller than the ones that feed the heart, the problem may show up earlier as having difficulty getting an erection.18


Qaseem, A., Snow, V., Denberg, T. D., Casey, D. E., Forciea, M. A., Owens, D. K., & Shekelle, P. (2009). Hormonal testing and pharmacologic treatment of erectile dysfunction: A clinical practice guideline from the American College of Physicians. Annals of internal medicine, 151(9), 639-649. Retrieved from http://annals.org/aim/article/745155/hormonal-testing-pharmacologic-treatment-erectile-dysfunction-clinical-practice-guideline-from
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Yet another common erectile dysfunction treatment that can be used in combination with oral drugs is a vacuum pump. This device consists of a plastic cylinder, a pump, a set of constriction bands, and a water-soluble lubricant. The lubricant is applied to the base of the penis to help form an airtight seal. The cylinder is placed over the flaccid penis and held tight against the pelvis. The pump is used to create a vacuum within the cylinder, drawing blood into the penis. Once the penis is engorged with blood, a constriction band is rolled off the cylinder to near the base of the penis. The constriction band is helpful for men with venous leakage, in which blood flows out of the penis as fast as it flows in. However, it should be left on for no more than 30 minutes at a time.
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