Associated morbidity may include various other male sexual dysfunctions, such as premature (early) ejaculation and male hypoactive sexual desire disorder. The NHSLS found that 28.5% of men aged 18-59 years reported premature ejaculation, and 15.8% lacked sexual interest during the past year. An additional 17% reported anxiety about sexual performance, and 8.1% had a lack of pleasure in sex. 
Medications: Many common medicines produce erectile dysfunction as a side effect. Medicines that can cause erectile dysfunction include many used to treat high blood pressure, antihistamines, antidepressants, tranquilizers, and appetite suppressants. Examples of common medicines that can cause erectile dysfunction include propranolol (Inderal) or other beta-blockers, hydrochlorothiazide, digoxin (Lanoxin), amitriptyline (Elavil), famotidine (Pepcid), cimetidine (Tagamet), metoclopramide (Reglan), naproxen, indomethacin (Indocin), lithium (Eskalith, Lithobid), verapamil (Calan, Verelan, Isoptin), phenytoin (Dilantin), gemfibrozil (Lopid), amphetamine/dextroamphetamine (Adderall), and phentermine. Prostate cancer medications that lower testosterone levels such as leuprolide (Lupron) may affect erectile function. Some chemotherapies such as cyclophosphamide (Cytoxan) may affect erectile function.
MSA is a neurodegenerative disease of undetermined etiology, where ED is an early prominent sign occurring in 40% of men at the time of diagnosis (46,47). ED occurs in the majority of patients and the exact cause of it is unknown (48). Like PD, MSA likely affects the dopaminergic pathways within the brain essential for arousal (49). Orthostatic hypotension (OH) as a causal factor has been refuted by evidence that sildenafil can overcome reduced filling pressures, and the ED usually precedes the development of OH (46,49,50). Similar to other neurologic disorders that lead to ED, other disease related factors such as psychosocial stress, the burden of chronic illness, changed appearance, fatigue, decreased fine motor movement of fingers, immobility and diminished self-esteem due to loss of independence may contribute as well (51).
Ultimately, PDE5i have had a significant impact on the treatment of ED in men with SCI. The ease of use and tolerability of the medication has also led to improved satisfaction and quality of life that had been previously affected by SD. Head to head trials evaluating specific PDE5i within the SCI population are required to further elucidate drug preference. PDE5i should be considered first line therapy, however men with high thoracic and cervical lesions should be warned about an increased chance of dizziness with sildenafil and possibly other PDE5i use.
Proper informed consent with your physician should be performed to understand all risks and benefits of hormonal replacement therapy. Follow-up testosterone (hormone) levels and periodic blood counts as testosterone therapy is associated with a risk of an abnormally high red blood cell count, and prostate checks are necessary for all men on long-term testosterone replacement therapy as there are concerns regarding the risk of testosterone therapy in men with an underlying prostate cancer. The use of testosterone therapy does not cause the development of prostate cancer. Testosterone therapy may increase the size of the prostate and cause urinary troubles.
There are myriad factors, both mental and physical, that may contribute to your erectile dysfunction symptoms. Some of the most common impotence causes include diabetes, hypertension, prostate problems, low testosterone and obesity, which can not only put a damper on your sexual enjoyment, but play a key role in your total male vitality, too. (Even medications that are often prescribed to control some of the aforementioned issues can be behind some of the frustrating symptoms of ED.) There are factors like depression, stress and anxiety that can leave you longing for your glory days, and the coping mechanisms like alcohol and tobacco that can make a roll in the sheets less satisfying for you and your partner. We’ll listen to you with a compassionate ear and thoughtfully consider what may be contributing to your ED symptoms, then draw up your perfect, personalized treatment.
Treatment depends on the underlying cause. In general, exercise, particularly of the aerobic type, is effective for preventing ED during midlife. Exercise as a treatment is under investigation.:6, 18–19 For tobacco smokers, cessation often results in a significant improvement. Oral pharmacotherapy and vacuum erection devices are first-line treatments,:20, 24 followed by injections of drugs into the penis, as well as penile implants.:25–26 Vascular reconstructive surgeries are beneficial in certain groups.
Nerve or spinal cord damage: Damage to the spinal cord and nerves in the pelvis can cause erectile dysfunction. Nerve damage can be due to disease, trauma, or surgical procedures. Examples include injury to the spinal cord from automobile accidents, injury to the pelvic nerves from prostate surgery for cancer (prostatectomy), and some surgeries for colorectal cancer, radiation to the prostate, surgery for benign prostatic enlargement, multiple sclerosis (a neurological disease with the potential to cause widespread damage to nerves), and long-term diabetes mellitus.
Normal erectile function depends on the release of NO and endothelial-dependent vasodilation of the penile arteries. The ‘artery size’ hypothesis, first described by Dr Montorsi, offers an explanation why men are more likely to develop ED before a myocardial infacrtion. It is believed that atherosclerosis affects all vascular beds equally but smaller arteries are more likely to become occluded than larger arteries.31 32 The penile arteries are 1–2 mm while the coronary arteries are 3–4 mm. Thus, the same degree of endothelial dysfunction and atherosclerosis is more likely to occlude blood flow in the penile arteries compared with the coronary arteries. The penile arteries therefore serve as a sensitive indicator for subsequent CVD. This theory is supported by the fact that ED occurs approximately 3 years prior to cardiac symptoms in virtually all patients with chronic coronary syndrome whereas patients with acute coronary syndrome have a much lower prevalence of sexual dysfunction.32
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.
Cosgrove et al reported a higher rate of sexual dysfunction in veterans with posttraumatic stress disorder (PTSD) than in veterans who did not develop this problem.  The domains on the International Index of Erectile Function (IIEF) questionnaire that demonstrated the most change included overall sexual satisfaction and erectile function. [43, 44] Men with PTSD should be evaluated and treated if they have sexual dysfunction.
Causes of impotence are many and include heart disease, high cholesterol, high blood pressure, obesity, metabolic syndrome, Parkinson's disease, Peyronie's disease, substance abuse, sleep disorders, BPH treatments, relationship problems, blood vessel diseases (such as peripheral vascular disease and others), systemic disease, hormonal imbalance, and medications (such as blood pressure and heart medications).
Male erectile problems often produce a significant emotional reaction based on the impact of erectile dysfunction on confidence, self-esteem, and morale in most men. This is described as a pattern of anxiety and stress that can further interfere with normal sexual function. Such "performance anxiety" needs to be recognized and addressed by a doctor.
Trauma to the pelvic blood vessels and nerves is another potential factor in the development of ED. Bicycle riding for long periods has been implicated, so some of the newer bicycle seats have been designed to soften pressure on the perineum (the soft area between the anus and the scrotum). Certainly, history of pelvic bone fracture, as well as previous pelvic surgery (orthopedic, vascular, colon-rectum, and prostate) may result in injury to the arteries or nerves that go to the penis.
Radical prostatectomy for the treatment of prostate cancer poses a significant risk of ED. A number of factors are associated with the chance of preserving erectile function. If both nerves that course on the lateral edges of the prostate can be saved, the chance of maintaining erectile function is reasonable. The odds depend on the age of the patient. Men younger than 60 years have a 75-80% chance of preserving potency, but men older than 70 years have only a 10-15% chance.
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.
Treatment involves addressing the underlying causes, lifestyle modifications, and addressing psychosocial issues. In many cases, a trial of pharmacological therapy with a PDE5 inhibitor, such as sildenafil, can be attempted. In some cases, treatment can involve inserting prostaglandin pellets into the urethra, injecting smooth muscle relaxants and vasodilators into the penis, a penile prosthesis, a penis pump, or vascular reconstructive surgery.
MedlinePlus : 43 Erectile dysfunction (ED) is a common type of male sexual dysfunction. It is when a man has trouble getting or keeping an erection. ED becomes more common as you get older. But it's not a natural part of aging. Some people have trouble speaking with their doctors about sex. But if you have ED, you should tell your doctor. ED can be a sign of health problems. It may mean your blood vessels are clogged. It may mean you have nerve damage from diabetes. If you don't see your doctor, these problems will go untreated. Your doctor can offer several new treatments for ED. For many men, the answer is as simple as taking a pill. Getting more exercise, losing weight, or stopping smoking may also help. NIH: National Institute of Diabetes and Digestive and Kidney Diseases
Recently, several advances in the uses of stem cells have bet met with great anticipation. Stem cells have the ability to differentiate into different cell lines based on the cellular signaling they receive. Bone marrow mononuclear cells in particular have been used for the treatment of ED in animal models. Yiou et al. recently delivered bone marrow-mononuclear cells (BM-MNC) into the intracavernous smooth muscle of post radical prostatectomy men (123). The open label, dose escalation phase I/II trial showed improvements in IIEF-15 assessment as well as increased vascularization of the corpora based on penile Doppler arterial velocity measurements. Although promising, further investigation in humans is required to substantiate BM-MNCs impact on erections, and erectile function recovery going forward.
Having erection trouble from time to time isn't necessarily a cause for concern. If erectile dysfunction is an ongoing issue, however, it can cause stress, affect your self-confidence and contribute to relationship problems. Problems getting or keeping an erection can also be a sign of an underlying health condition that needs treatment and a risk factor for heart disease.