Erectile dysfunction is the inability to develop or maintain an erection that is rigid enough to allow penetration of the vagina, and therefore functional sexual intercourse. Generally, the term erectile dysfunction is applied if this occurs frequently (75% of the time) over a significant period if time (several weeks to months). If this is the case, the term impotence may also be used.
Ejaculatory incompetence, erectile difficulty, erectile dysfunction, erectile failure, frigidity–female Medtalk The inability to achieve or maintain a penile erection adequate for the successful completion of intercourse, terminating in ejaculation; penile erection is mediated by nitric oxide Epidemiology Prevalence of minimal, moderate, and complete impotence in the Massachusetts Male Aging Study was 52%; age is the most important factor; complete impotence ↑ from 5%–age 40 to 15%–age 70; for an erection to achieve a successful outcome, it requires
Suppositories “were developed so men wouldn’t have to use needles,” Bivalacqua says. They contain the drug alprostadil (also known as prostaglandin E1) and are sold under the brand name Muse. If they are going to work, it takes about five to 10 minutes. However, Muse produces erections in only 30 to 40 percent of patients, usually those with mild ED, because some of the drug is absorbed systemically and diverted from its function of opening penile arteries to allow more blood to flow in. The out-of-pocket cost is around $20 to $30 per suppository.
Diabetes is a well-recognized risk factor for ED. A systematic review and meta-analysis found that the prevalence of ED was 37.5% in type 1 diabetes, 66.3% in type 2 diabetes, and 52.5% in diabetes overall—a rate approximately 3.5 times higher than that in controls.  The etiology of ED in diabetic men probably involves both vascular and neurogenic mechanisms. Evidence indicates that establishing good glycemic control can minimize this risk.
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.
There are many different body parts that play an important role for a man to get and maintain an erection during sexual intercourse. Beyond the physical causes that can lead to ED, it has been reported that 20% of ED is related to psychological causes.2 With so many possibilities leading to erectile dysfunction, it becomes particularly important to find a specialist who can correctly diagnosis the direct cause of your ED and find a treatment option that is right for you.
A larger national study, the National Health and Social Life Survey, looked at sexual function in men and women.4 This study surveyed 1,410 men aged 18 to 59 and also documented an increase in ED with age. Additionally, the study found a decrease in sexual desire with increasing age. Men in the oldest cohort (50 to 59) were more than 3 times as likely to experience erection problems and to report low sexual desire compared with men 18 to 29. Experience of sexual dysfunction was more likely among men in poor physical and emotional health. The study also concluded that sexual dysfunction is an important public health concern and that emotional issues are likely to contribute to the experience sexual dysfunction.
The dorsal artery provides for engorgement of the glans during erection, whereas the bulbourethral artery supplies the bulb and the corpus spongiosum. The cavernous artery effects tumescence of the corpus cavernosum and thus is principally responsible for erection. The cavernous artery gives off many helicine arteries, which supply the trabecular erectile tissue and the sinusoids. These helicine arteries are contracted and tortuous in the flaccid state and become dilated and straight during erection. 
Alprostadil should not be used in men with urethral stricture (scarring and narrowing of the tube that urine and the ejaculate pass through), balanitis (inflammation/infection of the glans [tip] of the penis, severe hypospadias (a condition where the opening of the urethra is not at the tip of the penis, rather on the underside of the penis), penile curvature (abnormal bend to the penis), and urethritis (inflammation/infection of the urethra).
Erectile dysfunction in older men. Because erections primarily involve the blood vessels, it is not surprising that the most common causes in older men are conditions that block blood flow to the penis, such as atherosclerosis or diabetes. Another vascular cause may be a faulty vein, which lets blood drain too quickly from the penis. Other physical disorders, as well as hormonal imbalances and certain operations, may also result in erectile dysfunction.
Some men report being helped by an oral medication called yohimbine, which comes from the bark of a tree that grows in India and Africa. This drug, which needs to be taken every day, has been reported to help about 20 to 25 percent of the men taking it. A relatively new but widely used oral medication called Viagra requires a careful medical evaluation by your doctor.
Several studies accessed the prevalence of ED. The Massachusetts Male Aging Study reported a prevalence of 52%.2 The study demonstrated that ED is increasingly prevalent with age: approximately 40% of men are affected at age 40 and nearly 70% of men are affected at age 70. The prevalence of complete ED increased from 5% at age 40 to 15% at age 70.2 Age was the variable most strongly associated with ED.
Conditions that may be associated with ED include diabetes, [25, 26, 27] hypertension,  , and CAD, as well as neurologic disorders, endocrinopathies, benign prostatic hyperplasia,  , sleep apnea  , COPD,  and depression (see Table 1 below). [32, 33, 34, 35] In fact, almost any disease may affect erectile function by altering the nervous, vascular, or hormonal systems. Various diseases may produce changes in the smooth muscle tissue of the corpora cavernosa or influence the patient’s psychological mood and behavior.
The most common inflatable prosthesis is the three-piece penile prosthesis. It is composed of paired cylinders, which doctors surgically insert inside the penis. Patients can expand the cylinders using pressurized fluid (see figure 3). Tubes connect the cylinders to a fluid reservoir and pump, which doctors also surgically implant. The reservoir is usually in the pelvis. A doctor places the pump in the scrotum. By pressing on the pump, sterile fluid transfers from the reservoir into the cylinders in the penis. An erection is produced primarily by expansion of the width of the penis, however, one model can increase in length a small amount also. Lock-out valves in the tubing prevent the fluid from leaving the cylinder until a release valve is pressed. By pressing the relief valve and gently squeezing the penis, the fluid within the cylinders transfers back into the reservoir.
inability of the male to achieve or maintain an erection of sufficient rigidity to perform sexual intercourse successfully. An impotent man may produce sufficient numbers of normal spermatozoa; the condition is related to infertility only insofar as it prevents coitus with and impregnation of the female partner. Called also erectile dysfunction. adj., adj im´potent.
ED can also occur among younger men. A 2013 study found that one in four men seeking their first treatment for ED were under the age of 40. The researchers found a stronger correlation between smoking and illicit drug use and ED in men under 40 than among older men. That suggests that lifestyle choices may be a main contributing factor for ED in younger men.
Alprostadil, a drug also discussed in Penile Injection Therapy, has been formulated into a small suppository. This applicator is inserted into the urethra (the canal through which urine and semen are excreted), and with compression of the applicator, the small suppository is released into the urethra. With massage/rubbing of the penis, the suppository dissolves in the urethra and the medication is absorbed into the penis where it acts to increase blood flow into the penis. One cannot use any form of lubricant (for example, K-Y jelly, Vaseline, etc) to help with the insertion of the suppository. Urinating prior to inserting the applicator will help moisten/lubricate the urethra.
You may find that using a vacuum device requires some practice or adjustment. Using the device may make your penis feel cold or numb and have a purple color. You also may have bruising on your penis. However, the bruises are most often painless and disappear in a few days. Vacuum devices may weaken ejaculation but, in most cases, the devices do not affect the pleasure of climax, or orgasm.
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.