When sexually stimulated there is a release of a chemical, nitric oxide (NO) in the blood vessels of the corpus cavernosum. The NO stimulates the production of a compound called cGMP, which causes relaxation of the smooth muscle in the blood vessels supplying the corpus cavernosum. PDE 5 is an enzyme that breaks down cGMP. By inhibiting the breakdown of cGMP by PDE5, these medications allow cGMP to build up in the penis. cGMP causes muscles in the corpora cavernosa of the penis to relax. When the muscle is relaxed, more blood can flow into the penis and fill the spaces in the penis. As the penis fills with blood, the veins in the penis are compressed, and this results a hard erection. When the effect on PDE5 decreases, the cGMP levels go down and the muscle in the penis contracts, causing less blood to flow into the penis and allowing the veins to open up and drain blood out of the penis.

Total testosterone levels: Health care professionals should obtain a patient's blood samples for total testosterone levels in the early morning (before 8 a.m.) because the testosterone levels go up and down throughout the day. If you have a low testosterone level, a health care professional should check it again to confirm that it is truly low. In some men, a specialized test measuring the active form of testosterone (free or bioavailable testosterone) may be recommended.
An erection involves the brain, nerves, hormones, muscles, and circulatory system. These systems work together to fill the erectile tissue in the penis with blood. A man with erectile dysfunction (ED) has trouble getting or maintaining an erection for sexual intercourse. Some men with ED are completely unable to get an erection. Others have trouble maintaining an erection for more than a short time.
 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. 
This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. The NIDDK translates and disseminates research findings through its clearinghouses and education programs to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by the NIDDK is carefully reviewed by NIDDK scientists and other experts.
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.
The article, "Inactivation of phosphorylated endothelial nitric oxide synthase (Ser-1177) by O-GlcNAc in diabetes-associated erectile dysfunction," appears in the Aug. 16 issue of the Proceedings of the National Academy of Sciences and was published online Aug. 5.  Melissa F. Kramer and Robyn E. Becker, also of the Brady Urological Institute, collaborated on this study.
Surgery for erectile dysfunction is usually considered only after all other options have failed. The two surgical options include the insertion of a semi-rigid rod or the implantation of a three-piece inflatable prosthesis. Penile prosthesis implantation has low infection, complication, and malfunction rates. However, since placement of an implant requires permanent injury to the erectile tissue of the penis, implant treatment is considered irreversible.
The best policy is honesty and clarity. If you understand the cause of your ED, as well as the solution, you can enlighten your partner and allow both of you to enjoy sexual intimacy along with everything else you both enjoy about each other. It doesn’t have to be a secret shame, because it’s a medical condition just like any other and fortunately its very treatable.
If you have been diagnosed with depression, stress or anxiety and do not want to take an anti-depressant or anxiety medication due to the side effects, then Mind Over ED, by Joel Block, MD might be the remedy for you.   This natural technique requires no pills, and uses your mind to help you overcome many of the issues that cause erectile dysfunction permanently.  If you already suffer from impotence as a result of your mental issues, drugs that treat these condition also lead to erectile dysfunction, so you will be on a never ending chase to cure your erection problems.  I have been using this technique for three years.  It cured my stress and anxiety quickly and naturally.  Read more about it here.
Medications used to treat high blood pressure (hypertension), including diuretics and beta-blockers, may cause ED. Not all blood pressure medications are associated with ED; alpha-blockers, ACE inhibitors, calcium channel blockers, and angiotensin II receptor blockers don't appear to cause ED. If you are on a blood pressure medication, have an ED talk with your doctor about whether or not your medication may be contributing to your ED and if there is an alternative blood pressure medication that is safe for you to try.
Illegal drugs don’t just affect and suppress the central nervous system. They cause serious damage to blood vessels. And any damage to blood vessels or normal blood flow will eventually cause erectile dysfunction. Some experts even argue that a single use of any of these chemicals can lead to subsequent ED. Chronic use raises the risk even more. If you have a substance addiction speak to your physician. There’s always help available.
Additionally, speaking to more than just the sexual issues related to erectile dysfunction, the research addresses implications related to the overall understanding of penile health. According to Arthur Burnett, M.D., a professor of urology and head of the research team, "eNOS plays roles in both immediate erectile response and the overall health and function of the penile tissue." 
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:
ED is common among patients with cardiovascular diseases (CVD). Sexual problems usually precede the onset of CVD, and should, therefore, be considered as a risk factor for cardiac events. Similarly, patients with preexisting CVD are at increased risk of experiencing ED. Therefore, ED and CVD might be considered as two different clinical manifestations of the same systemic disease.19
In many ways, performance anxiety becomes a self-fulfilling prophecy wherein you become nervous about being able to satisfy your partner and the nerves lead to sexual dysfunction. In many cases, performance anxiety is triggered by negative self-talk – worries about being able to achieve an erection, pleasing a partner, or ejaculating too early. If you have had erectile issues in the past, those experiences will add to the weight of performance anxiety.
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.
The association between psychiatric conditions and sexual dysfunctions, including ED, is well known. Data from population-based studies demonstrate a cross-sectional association between depressive symptoms and ED (65-68) and, among men seeking medical care for ED, depression is significantly associated with a greater severity of the impairment in erectile function (69,70). A meta-analysis of the available prospective studies has shown the role of depression as a significant risk factor for development of ED (71). However, the relationship seems to be bidirectional, as also ED has been associated with the occurrence of depression (72). In addition, treatment with PDE5i is related with an improvement in depressive symptoms (72). Most of this evidence comes from studies not specifically designed for the assessment of this relationship in younger men. However, few studies available in younger populations seem to confirm these results. In an internet-based survey, involving more than 800 North American medical students with a mean age of 25.7 years, ED was reported by 13% of them and it showed a significant association with depressive symptoms, whose frequency got higher as a function of ED severity (73). In a population of more than 2,500 very young Swiss men, aged 18–25 years, participating to a survey on sexual function while attending the medical screening for the evaluation of military capability, ED had a prevalence of 30%. Among the possible correlated conditions, mental health showed an independent association, besides the use of medications without medical prescription, a shorter sexual lifespan and impaired physical health (74). The results from this Swiss study were then prospectively extended on a sample of 3,700 men evaluated at baseline and 15.5 months later (75). Among a number of different possible predictors, including life-style, drug abuse, perceived physical fitness and BMI, only perceived impairment in mental health and depression, either newly occurred or continuously present, were associated with both persistence and development of ED (75). In a retrospective population-based study from Finland, involving almost 3,500 men aged 18–48 years, the role of depression as a significant predictor for ED was confirmed, but this study also showed that anxiety plays a significant role and that ED is significantly less frequent in men with a longer lasting sexual life, thus underlining the positive role of sexual experience and self-confidence (76). Anxiety is often involved in the pathogenesis of ED at the beginning of sexual life. In fact, anxiety can lead to an excessive focus on quality of erection, thus providing a cognitive distraction that negatively affects the arousal and consequently the erection itself (77-79). On the other hand, anxiety can result from one or more sexual failures, with loss of sexual confidence, increasing fears and avoidance for sexual experiences that, in the end, lead to an increased probability of new failures, thus creating a vicious circle (77). Cognitive distraction could be also provided by excessive worry for physical, and in particular genital, self-image. In fact, it has been proposed that when most mental energy is focused on monitoring body, psychological resources are distracted from sex, resulting in an impaired functioning (80,81). In line with this cognitive explanation, a recent study conducted on 367 military personnel younger than 40 years showed that a deteriorated genital self-image is associated with sexual anxiety which, in turn, is associated with a higher probability of sexual dysfunction (82).

In some cases, ED can be a warning sign of more serious disease. One study suggests ED is a strong predictor of heart attack, stroke, and death from cardiovascular disease. The researchers say all men diagnosed with ED should be evaluated for cardiovascular disease. This does not mean every man with ED will develop heart disease, or that every man with heart disease has ED, but patients should be aware of the link.


Venous leak occurs when veins are unable to keep enough blood in the penis for a suitable erection.  As noted above, a firm erection results when blood flows into the penis.  Veins normally constrict to keep the blood inside until the man ejaculates.  A venous leak prevents blood from staying in the penis.  Instead, blood leaks back into the body and the erection fails to stay rigid.
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