Not to give your already stressed-out dude one more thing to worry about, but stress is the cause of 20 percent of all erectile problems, from one-off boner blunders to a lingering inability to get and maintain an erection. Of course, sex difficulties are just the tip of the stress-induced health problem iceberg — sustained stress can also lead to insomnia, stomach troubles, chest pains, anxiety, and more severe health issues in the long term.
Psychological factors on their own are estimated to be the cause of 20% of all the cases of erectile dysfunction and account for most of the difficulties in young men. They can also contribute towards its continuation in all age groups where physical causes are the main culprit, but the man’s reaction to what he sees as his “failure” has added a psychological impact.
Thanks for your question, Frightened Turtle! To help answer it, we spoke with Dr. Darius Paduch, urologist and male sexual medicine specialist at New York Presbyterian/Weill Cornell Medical Center, and sex therapist Jenni Skyler, Ph.D., director of The Intimacy Institute for sex and relationship therapy in Boulder, Colorado. Here's what they had to say:
In comparison, 37% of men who had received external radiotherapy as their primary therapy reported the ability to attain functional erections suitable for intercourse, along with 43% of men who had received brachytherapy as primary treatment. Pretreatment sexual health-related quality of life score, age, serum prostate-specific antigen (PSA) level, race or ethnicity, body mass index, and intended treatment details were associated with functional erections 2 years after treatment. 
This consensus development conference on male erectile dysfunction has provided an overview of current knowledge on the prevalence, etiology, pathophysiology, diagnosis, and management of this condition. The growing individual and societal awareness and open acknowledgment of the problem have led to increased interest and resultant explosion of knowledge in each of these areas. Research on this condition has produced many controversies, which also were expressed at this conference. Numerous questions were identified that may serve as foci for future research directions. These will depend on the development of precise agreement among investigators and clinicians in this field on the definition of what constitutes erectile dysfunction, and what factors in its multifaceted nature contribute to its expression. In addition, further investigation of these issues will require collaborative efforts of basic science investigators and clinicians from the spectrum of relevant disciplines and the rigorous application of appropriate research principles in designing studies to obtain further knowledge and to promote understanding of the various aspects of this condition.
If you have unstable heart disease of any kind, heart failure or unstable, what we call angina, contraindication to using the medications. All right? So if you’re in an unstable medical state, these medications are not a good idea. Now, there are relative issues. If you may be taking a blood pressure medicine or a medicine for your prostate which dilates your blood vessel a little bit– you know, the typical ones are what we call the alpha blockers– you may have an additive effect from the medication. But for the most part, the medicines are incredibly safe.
Physicians make a diagnosis of erectile dysfunction in men who complain of troubles having a hard enough erection or a hard erection that does not last long enough. It is important as you talk with your doctor that you be candid in terms of when your troubles started, how bothersome your erectile dysfunction is, how severe it is, and discuss all your medical conditions along with all prescribed and nonprescribed medications that you are taking. Your doctor will ask several questions to determine if your symptoms are suggestive of erectile dysfunction and to assess its severity and possible causes. Your doctor will try to get information to answer the following questions:
NO is produced by the enzyme NO synthase (NOS).  NOS plays many roles, ranging from homeostasis to immune system regulation. To date, 3 subtypes have been identified: nNOS, iNOS, and eNOS, which are produced by the genes NOS1, NOS2, and NOS3, respectively. This nomenclature is derived from the sources of the original isolates: neuronal tissue (nNOS), immunoactivated macrophage cell lines (iNOS), and vascular endothelium (eNOS). The subtypes are not, however, limited to the tissues from which they were first isolated.
Injection of vasodilator substances into the corpora of the penis has provided a new therapeutic technique for a variety of causes of erectile dysfunction. The most effective and well-studied agents are papaverine, phentolamine, and prostaglandin E[sub 1]. These have been used either singly or in combination. Use of these agents occasionally causes priapism (inappropriately persistent erections). This appears to have been seen most commonly with papaverine. Priapism is treated with adrenergic agents, which can cause life-threatening hypertension in patients receiving monoamine oxidase inhibitors. Use of the penile vasodilators also can be problematic in patients who cannot tolerate transient hypotension, those with severe psychiatric disease, those with poor manual dexterity, those with poor vision, and those receiving anticoagulant therapy. Liver function tests should be obtained in those being treated with papaverine alone. Prostaglandin E[sub 1] can be used together with papaverine and phentolamine to decrease the incidence of side effects such as pain, penile corporal fibrosis, fibrotic nodules, hypotension, and priapism. Further study of the efficacy of multitherapy versus monotherapy and of the relative complications and safety of each approach is indicated. Although these agents have not received FDA approval for this indication, they are in widespread clinical use. Patients treated with these agents should give full informed consent. There is a high rate of patient dropout, often early in the treatment. Whether this is related to side effects, lack of spontaneity in sexual relations, or general loss of interest is unclear. Patient education and followup support might improve compliance and lessen the dropout rate. However, the reasons for the high dropout rate need to be determined and quantified.
In addition, a man affected by lower testosterone may feel less sexually inclined, less interested in viewing sexual material, and less interested in physical activities. To add to this, a man dealing with less testosterone may also become less assertive, more inclined to stay in, and more likely to seek out medical help for his erectile dysfunction.
ED means no erections from masturbation. According to the American Urological Association, ED is “the inability to achieve or maintain an erection sufficient for satisfactory sexual performance.” Huh? That’s absurdly vague. If you define “an erection” as what you see in porn, and “satisfactory sexual performance” as porn sex—instant, hard-as-rock erections that last forever with climaxes always on cue—then just about every guy has ED. What is ED, really? For practical purposes, it means that a man who’s sober (no alcohol or other erection-impairing drugs) cannot raise even a semi-firm erection after extended masturbation.
Recently, the US Food and Drug Administration (FDA) has issued a safety announcement regarding TRT. In part it reads ‘The benefit and safety of these medications have not been established. We are also requiring these manufacturers to add information to the labeling about a possible increased risk of heart attacks and strokes in patients taking testosterone.’37
If you just got off solo, you might have to wait before you can hop into bed with your partner, says Dr. Brahmbhatt. It might have something to do with a spike in the hormone prolactin after you orgasm, according to a study published in the International Journal of Impotence Research. This hormone has been linked to difficulties maintaining an erection or even ejaculating.
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.