A sexually competent male must have a series of events occur and multiple mechanisms intact for normal erectile function. He must 1) have desire for his sexual partner (libido), 2) be able to divert blood from the iliac artery into the corpora cavernosae to achieve penile tumescence and rigidity (erection) adequate for penetration, 3) discharge sperm and prostatic/seminal fluid through his urethra (ejaculation), and 4) experience a sense of pleasure (orgasm). A man is considered to have ED if he cannot achieve or sustain an erection of sufficient rigidity for sexual intercourse. Most men, at one time or another during their life, experience periodic or isolated sexual failures. However, the term “impotent” is reserved for those men who experience erectile failure during attempted intercourse more than 75% of the time.
For many young men, performance anxiety plays a large role in erectile dysfunction. Other factors include money and work problems, as well as relationship issues and even issues about sexual orientation. Undiagnosed depression and post-traumatic stress disorder can cause erectile dysfunction--especially if the PTSD is related to a past sexual experience.
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"One of the reasons erectile dysfunction increases with age is that the diseases that lead to it also increase with age," notes Dr. Feloney. Evaluating the causes of erectile dysfunction starts with your doctor taking a good health history and giving you a physical exam. Common medical issues that can lead to erectile dysfunction include diabetes, high blood pressure, hardening of the arteries, low testosterone, and neurological disease. Talk to your doctor about better managing these health conditions.

Monitoring erections that occur during sleep (nocturnal penile tumescence) can help you and your doctor to understand if the erectile dysfunction is due to psychological or physical causes. The nocturnal penile tumescence test is a study to evaluate erections at night. Normally men have three to five erections per eight hours of sleep. The test can be performed at home or in a sleep lab. The most accurate way to perform the test involves a special device that is connected to two rings. The rings are placed around the penis, one at the tip of the penis and the other at the bottom (base) of the penis. The device records how many erections occur, how long they last, and how rigid they are. The test is limited in that it does not assess the ability to penetrate.
Lifestyle choices that impair blood circulation can contribute to ED. Smoking, excessive drinking, and drug abuse may damage the blood vessels and reduce blood flow to the penis. Smoking makes men with atherosclerosis particularly vulnerable to ED. Being overweight and getting too little exercise also contribute to ED.  Studies indicate that men who exercise regularly have a lower risk of ED.
Unconventional CV risk factors, such as impaired erections during masturbation and reduced flaccid acceleration, are interesting parameters to implement in Sexual Medicine context, because they can help fill the gap of information on CV risk, left by the conventional risk factors (the so-called residual risk) (38). However, it should be recognized that not all the healthcare professionals who deal with the complaint of ED (i.e., general practitioners, diabetologists, cardiologists, sport physicians, nurses, etc.) have the facilities or competence for the specific assessment of these parameters. In contexts different than Sexual Medicine and Andrology, the assessment of conventional risk factors is certainly more convenient. Metabolic syndrome (MetS) represents a cluster of metabolic derangements easily and commonly evaluated in several different medical contexts. In a population of more than 600 subjects attending the Sexual Medicine and Andrology Unit of the University of Florence for ED, the presence of MetS was associated with an increased incidence of MACE during 4.3 years of follow-up in younger (first tertile of age: 18–52 years) (Figure 3, Panel A and B) but not in middle aged and older men (second and third tertiles of age: 53–60 and 61–88 years, respectively) (Figure 3, Panel B). Similar to MetS, the algorithms for estimating the risk of developing MACE are easily computed and they take into account factors largely available in a clinical setting. In Europe, the most commonly used algorithm is the SCORE, which takes into account age, smoking habits, systolic blood pressure and total cholesterol (26). These parameters are introduced in a calculation tool that returns the 10-year risk of developing the first MACE. The same estimated risk rate can obviously be derived from different combinations and extent of the single risk factors and, as aforementioned, age has a heavy weight in the amount of risk, even when the other parameters are normal. For overcoming this overestimation, the concept of vascular age, based on the predicted CV risk, has been introduced. Vascular age of a subjects with a specific CV risk profile corresponds to the chronological age of a subjects who has the same estimated risk but only due to chronological age, because of the absence of the other modifiable risk factors (i.e., a non-smoker, normotensive and normocholesterolemic subject) (39,40). Vascular age carries the advantage of easily and directly communicating the concept of high relative risk to patients, in particular to younger ones, who are by definition at low absolute risk (“Your CV risk is the same of a man that is 15 years older than you”). Based on this interesting and useful concept of vascular age, we recently studied the clinical consequences of having a high discrepancy between the estimated vascular and the actual chronological age in our population of men consulting for ED. In our sample, a greater difference between vascular and chronological age was associated with higher glucose and triglyceride levels as well as with impaired penile colour Doppler ultrasound parameters, suggesting a CV impairment (41). When evaluating the subset of men for whom information on incident MACE during a mean follow-up of 4.3 years was available, a greater difference between vascular and chronological age was associated with the incidence of MACE in younger, but not in older men (42).
Sildenafil is available as oral tablets at doses of 25 mg, 50 mg, and 100 mg. Patients should take sildenafil approximately one hour before sexual activity. In some men, the onset of action of the drug may be as early as 11-20 minutes. It's best for men to take sildenafil on an empty stomach for best results since absorption and effectiveness of sildenafil can be diminished if it is taken shortly after a meal, particularly a meal that is high in fat. Sildenafil and the other PDE5 inhibitors don't cause an immediate erection. Sexual stimulation is necessary for these medications to work.
 Other treatment options such as penile self-injection therapy, external vacuum pumps and the medicated urethral system for erection are on rare occasions an effective long-term treatment. A very small percentage of men will continue with these treatments as evidenced by a very high drop out rate and a very low refill rate for these treatments. These procedures require extensive planning which interfere with sexual spontaneity and are really not a realistic long-term treatment for young patients with permanent ED. 
Combination therapy has proven effective for some men who don’t respond adequately to oral medicines. The idea is to use two drugs with different mechanisms of action for better results. Commonly, sildenafil is used in combination with pellets of alprostadil (synthetic prostaglandin E1) that are inserted into the urethra (the tube in the penis that carries urine from the bladder to the outside of the body). Alprostadil also increases the blood supply to the penis, but by different means.

Dr. Niket Sonpal is the Associate Program Director of the Internal Medicine Residency at Brookdale Hospital Medical Center in Brooklyn and an Associate Professor at Touro College of Osteopathic Medicine. He’s a practicing Gastroenterologist and Hepatologist with a focus on Men’s and Women’s Health, and a regular contributor to Women’s health, Shape and Prevention Magazine.
For obvious reasons, ED can be a sensitive subject, one that until relatively recently men were more likely to try to hide than to deal with. Fortunately, a deeper understanding of the variety of causes of erectile dysfunction has led to medications, therapies, and other treatments that can be more individualized and more likely to be effective—and more open discussion about addressing the concern.

But don’t panic. ED can be caused by a number of factors, from depression and medication side effects to high blood pressure, high cholesterol, low testosterone levels, Peyronie’s disease, nerve damage, performance anxiety, heart disease, diabetes, and more. Even better, many of these ED causes are treatable with medication and simple lifestyle changes. It’s important to know the root cause of your erectile dysfunction in order to treat it in the fastest, most effective way possible. Here are the 5 most common causes of erectile dysfunction.
In the evaluation of physical causes of ED, the health care provider is assessing for conditions that may affect the nerves, arteries, veins, and functional anatomy of the penis (for example, the tunica albuginea, the tissue surround the corpora). In determining a physical (or organic) cause, your health care provider will first rule out certain medical conditions, such as high blood pressure, high cholesterol, heart and vascular disease, low male hormone level, prostate cancer, and diabetes, which are associated with erectile dysfunction. Medical/surgical treatment of these conditions may also cause ED. In addition to these health conditions, certain systemic digestive (gastrointestinal) and respiratory diseases are known to result in erectile dysfunction:
While erectile dysfunction can occur at any age, the risk of developing erectile dysfunction increases with age. According to the Massachusetts Male Aging Study, the prevalence of erectile dysfunction was 52% in men 40-70 years of age. The prevalence of complete erectile dysfunction increases from 5% at 40 years of age to 15% among men 70 years of age and older.

Dr. Niket Sonpal is the Associate Program Director of the Internal Medicine Residency at Brookdale Hospital Medical Center in Brooklyn and an Associate Professor at Touro College of Osteopathic Medicine. He’s a practicing Gastroenterologist and Hepatologist with a focus on Men’s and Women’s Health, and a regular contributor to Women’s health, Shape and Prevention Magazine.
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).

The various PDE5 inhibitors for the treatment of ED share several common side effects, including headache, flushing, nasal congestion, nausea, dyspepsia (stomach discomfort), and diarrhea. Differences exist in side effects of the different PDE5 inhibitors, and thus it is important to be familiar with the prescribing information of the PDE5 inhibitor you are prescribed.
In patients with low testosterone, testosterone treatment can improve libido and erectile dysfunction, but many men still may need additional oral medications such as sildenafil, vardenafil, or tadalafil. Some studies suggest that men with ED and low testosterone may respond better to PDE5 inhibitors when given testosterone therapy; however, this is controversial.

Ultrasound with Doppler imaging (ultrasound plus evaluation of blood flow in the arteries and veins) can provide additional information about blood flow of the penis and may help in the evaluation of patients prior to surgical intervention. This study is typically performed after the injection of a chemical that causes the arteries to open up, a vasodilator (prostaglandin E1), into the corpora cavernosa in order to cause dilation of blood vessels and promote blood flow into the penis. The rate of blood flow into the penis can be measured along with an evaluation of problems with compression of the veins.


"We used to think that ED in young men was 90 percent psychological, but we now know that most cases are caused by a combination of risk factors. Erectile function depends on hormones, blood supply, nerve function, and psychological health,” said Run Wang, MD, professor of urology at The University of Texas Health Science Center in Houston and director of sexual medicine at MD Anderson Cancer Center.
Diabetes can cause nerve, blood vessel, and muscle damage that results in problems like pain, numbing or loss of sensation in the hands and feet.12 These issues can also result in ED problems, because nerve signals and blood flow are necessary to the process of getting an erection.6 And as men with diabetes get older, ED problems become even more common.13
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.
Talk with your doctor before trying supplements for ED. They can contain 10 or more ingredients and may complicate other health conditions. Asian ginseng and ginkgo biloba (seen here) are popular, but there isn't a lot of good research on their effectiveness. Some men find that taking a DHEA supplement improves their ability to have an erection. Unfortunately, the long-term safety of DHEA supplements is unknown. Most doctors do not recommend using it.
Care for these patients, who in many cases are emotional, demanding, and time consuming, may evoke feelings of frustration and anticipatory anxiety in the time-strapped urologist. Early in the encounter, the urologist must understand the patient’s psychosocial environment and establish a rapport and meaningful alliance with the patient and his family, if present (13). It is important to ensure that the doctor-patient interaction is informative and task oriented for greater patient buy-in and compliance with treatment (13,14). Affirm to the patient that regardless of the short time allotted for the visit that the doctor-patient relationship will endure even after the visit. This may be accomplished through a scheduled follow-up telephone call, electronic message, follow-up clinic visit, or a written letter. It may also be beneficial to refer the patient to a sex therapist or counselor though many young men will reject the idea that there is a psychosocial element to their ED and may refuse to consider therapy.

Inflatable prostheses are complex mechanical devices that imitate the natural process of erection. Parts are inserted surgically into the penis and scrotum, and activated by squeezing. When erection is no longer desired, a valve on the pump is pressed, and the penis becomes flaccid. Self-contained single-unit prostheses are similar to the inflatable types, but more compact. The entire device is implanted into the penis. When erection is desired, the unit is activated by either squeezing or bending, depending on which of the two types of self-contained prostheses is used.

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