Dr. Liou says that some men come to him after getting a prescription from their primary care doctors, claiming that the drug doesn't work. Sometimes it's because they used it incorrectly. "The biggest misconception is that these drugs are an on/off switch for erections," Dr. Liou says. But the drugs don't work well without sexual stimulation. "During that time, you need to be with your partner and have foreplay," Dr. Liou says. "Don't take it, do the taxes or the dishes, and then meet at the bedroom thinking you'll be ready to go. It's not like that."
Many men gain potency by injecting drugs into the penis, causing it to become engorged with blood. Drugs such as papaverine hydrochloride, phentolamine, and alprostadil (marked as Caverject) widen blood vessels. These drugs may create unwanted side effects, however, including persistent erection (known as priapism) and scarring. Nitroglycerin, a muscle relaxant, sometimes can enhance erection when rubbed on the surface of the penis.
A common and important cause of ED is vasculogenic. Many men with ED have comorbid conditions such as hyperlipidemia, hypercholesterolemia, tobacco abuse, diabetes mellitus, or coronary artery disease (CAD).  The Princeton III Consensus recommends screening men who present with ED for cardiovascular risk factors; ED may be the earliest presentation of atherosclerosis and vascular disease. 
Under normal circumstances, when a man is sexually stimulated, his brain sends a message down the spinal cord and into the nerves of the penis. The nerve endings in the penis release chemical messengers, called neurotransmitters, that signal the corpora cavernosa (the two spongy rods of tissue that span the length of the penis) to relax and fill with blood. As they expand, the corpora cavernosa close off other veins that would normally drain blood from the penis. As the penis becomes engorged with blood, it enlarges and stiffens, causing an erection. Problems with blood vessels, nerves, or tissues of the penis can interfere with an erection.
The National Institutes of Health Consensus Development Conference on Impotence was convened to address (1) the prevalence and clinical, psychological, and social impact of erectile dysfunction; (2) the risk factors for erectile dysfunction and how they might be used in preventing its development; (3) the need for and appropriate diagnostic assessment and evaluation of patients with erectile dysfunction; (4) the efficacies and risks of behavioral, pharmacological, surgical, and other treatments for erectile dysfunction; (5) strategies for improving public and professional awareness and knowledge of erectile dysfunction; and (6) future directions for research in prevention, diagnosis, and management of erectile dysfunction. Following 2 days of presentations by experts and discussion by the audience, a consensus panel weighed the evidence and prepared their consensus statement.
Chronic stress dumps adrenaline in your system multiple times a day. And that can lead to high blood pressure, heart disease, obesity, and diabetes. Chronic stress is like red-lining your car all day long. When you drive 100 mph all the time, something is going to break down. A high-stress environment can actually change the way your brain sends messages to your body. Dumping too much adrenaline into your bloodstream can affect blood flow and severely limit your ability to achieve and maintain an erection.
If you are taking medications (alpha-blockers) for problems with an enlarged prostate, you should discuss your prostate medications with your doctor. Alpha-blockers also can cause lowering of the blood pressure. Thus your doctor will need to carefully watch your blood pressure when you start the PDE5 inhibitor. Common alpha-blockers include doxazosin (Cardura), terazosin (Hytrin), and tamsulosin (Flomax).
Depression and anxiety: Psychological factors may be responsible for erectile dysfunction. These factors include stress, anxiety, guilt, depression, widower syndrome, low self-esteem, posttraumatic stress disorder, and fear of sexual failure (performance anxiety). It is also worth noting that many medications used for treatment of depression and other psychiatric disorders may cause erectile dysfunction or ejaculatory problems.
Willful and capricious – erections are funny things. When you're a young man, they seem to pop up at the most inappropriate moments (and the only thing between you and embarrassment is a carefully placed notebook). As you get older, however, they go the other way, and fail to appear on demand no matter how much you try. The sad thing is, my patients often equate this with a loss of masculinity.
Erectile dysfunction is often assumed to be a natural concomitant of the aging process, to be tolerated along with other conditions associated with aging. This assumption may not be entirely correct. For the elderly and for others, erectile dysfunction may occur as a consequence of specific illnesses or of medical treatment for certain illnesses, resulting in fear, loss of image and self-confidence, and depression.
In a randomized double-blind, parallel, placebo-controlled trial, sildenafil plus testosterone was not superior to sildenafil plus placebo in improving erectile function in men with ED and low testosterone levels.  The objective of the study was to determine whether the addition of testosterone to sildenafil therapy improves erectile response in men with ED and low testosterone levels.
Another study compared the response of surgically and medically castrated rabbits to vardenafil with that of control rabbits.  Castrated rabbits did not respond to vardenafil, whereas noncastrated rabbits did respond appropriately. This result suggests that a minimum amount of testosterone is necessary for PDE5 inhibitors to produce an erection.
Years ago, the standard treatment for impotence was an implantable penile prosthesis or long-term psychotherapy. Although physical causes are now more readily diagnosed and treated, individual or marital counseling is still an effective treatment for impotence when emotional factors play a role. Fortunately, other approaches are now available to treat the physical causes of impotence.
Whenever I am prescribing a medication to a patient, I’m always asking myself, what can the patient do before requiring the medication? What changes do they have to make in order to reduce the amount of medication or preclude their even needing it? So a good candidate is somebody who has an understanding of a healthy lifestyle, about physical activity, about sleep, about nutrition, alcohol, smoking. So patients, individuals, have to do their share before they’re a candidate for anything. All right?
You're not hard. You're about to have sex for the first time with your date, who's truly beautiful. All you want to do is present your glorious, super strong erection and let it do the talking. And yet when you look down, you're limp instead of hard. This doesn't make any sense! you think. Every element you could possibly need for an erection is here. Nudity, beauty, passion, the tantalizing thrill of boning someone for the first time, and a little bit of booze to take the edge off. What on earth is wrong and why are you so unlucky? You turn to your date. "I swear, this never happens..."
Many factors can contribute to sexual dysfunction in older men, including physical and psychological conditions, comorbidities and the medications used to treat them. Aspects of an ageing man’s lifestyle and behaviour and androgen deficiency, most often decreasing testosterone levels, may affect sexual function as well. A study of men between the ages of 30 and 79 years showed that 24% had testosterone levels below 300 ng/dL and 5.6% had symptomatic androgen deficiency.2
The risk of impotence increases with age. It is four-fold higher in men in their 60s compared with those in their 40s according to a study published in the Journal of Urology (2000;163:460-463). Men with less education are also more likely to experience impotence, perhaps because they tend to have less healthy lifestyles, eat a less healthy diet, drink more and exercise less. Physical exercise tends to lessen the risk of impotence.
Infection is a concern after placement of a prosthesis and is a reported complication in 8%-20% of men undergoing placement of a penile prosthesis. If a prosthesis becomes infected (redness, pain, and swelling of the penis and sometimes purulent drainage are signs of infection), the prosthesis must be removed. Depending on the timing and severity of the infection and your surgeon's preference, the area can be irrigated extensively with antibiotic solutions and a new prosthesis placed at the same time or removal of the infected prosthesis and an attempt to place a new prosthesis made at a later time when the infection is totally cleared.
Vascular: Anything that affects the flow of blood to the penis can result in erectile dysfunction. The main culprit tends to be atherosclerosis, the condition that narrows arteries and which can result in poor blood circulation, high blood pressure, heart disease and stroke. Atherosclerosis causes about half the cases of erectile dysfunction in men over 50. Also, the veins through which the blood leaves the penis may not be working properly, allowing the blood to leave too soon.
The circulatory system plays a central role in obtaining and sustaining erections. Augmentation of blood flow to the corporal bodies depends on the intravascular pressure in the penile artery. Vascular lesions—typically atherosclerotic, but occasionally fibrotic—and systemic hypotension will limit flow to the corpora. In certain patients, blood flow at rest may be sufficient to obtain an erection but not sufficient to maintain it during intercourse, when the pelvic musculature places greater demands on a compromised blood supply.
Normal Male Sexual Ageing is ignored by health care professionals. There is never a clear discussion. The best that happens is that when it happens, instead of Male Sexual Decline being a known factor that should be quantified for each individual male by regular testing and awareness, the health care professional says, "Oh. This is normal.You can do other things and still keep sex enjoyable".
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).
In the short term, alcohol relaxes muscles in the penis, letting blood to flow in (which is a good thing). However, alcohol also prevents other blood vessels from closing and trapping all the extra blood. Erections depend on trapping increased blood flow in the erectile tissue of the penis. If you don’t trap that extra blood, you don’t get an erection. In the long run, excessive alcohol consumption can cause liver scarring, high blood pressure, and can damage your blood vessels resulting in erectile dysfunction.