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.
The causes of ED are numerous but generally fall into two categories: organic or psychogenic. The organic causes can be subdivied into five categories: vascular, traumatic/postsurgical, neurological, endocrine-induced, and drug-induced. Examples of the psychogenic causes are depression, performance anxiety, and relationship problems. In people with diabetes, the main risk factors are neuropathy, vascular insufficiency, poor glycemic control, hypertension, low testosterone levels, and possibly a history of smoking.
For patients who have ED related to hypertonic cavernous smooth muscle and excessive sympathetic discharge, we recommend a trial of a low-dose alpha adrenergic blocker, such as terazosin 1 mg PO at bedtime nightly. We typically increase the dosage as needed every 2–3 weeks for 3–5 months until the patient experiences improvement of the erection or we determine that treatment is ineffective. We explain the potential side effects of orthostasis, dizziness, and retrograde ejaculation in detail. We also take great care and time in explaining to the patient, and his family/partner if present, the pathophysiologic mechanism of their erectile dysfunction and the biological basis of the treatment plan. This detailed discussion helps to engage the patient in the treatment plan and provides encouragement regarding the potential for response to treatment and recovery. During these encounters, we utilize teaching tools, such as diagrams, drawings, printed handouts, and other visual aids to ensure that the discussion is patient-focused and patient-friendly. Patient education is critical to exploring treatment options and developing confidence in our ability to treat the ED, and their own ability to overcome and eventually resolve the problem of ED.
This category of treatments includes external vacuum therapies: devices that go around the penis and produce erections by increasing the flow of blood in, while constricting the flow out. Such devices imitate a natural erection, and do not interfere with orgasm. External vacuum therapy mechanisms are approximately 95 percent successful in causing and sustaining an erection. All are portable, and costs range between $200-$500, covered under most insurance plans and Medicare Part B.
The number of sexual dysfunction complaints was significantly associated with the amount of alcohol consumed per day. On curve-fitting the data, there was a significant positive linear relationship (F = 10.54; dF 87; P = 0.002) [Figure 1]. However, there was no correlation between the reduction in frequency of sexual intercourse over the last five years and the amount of alcohol consumed.

Diabetes is known to sabotage two body parts that provide essential components of an erection: nerves and blood vessels. Studies suggest that diabetic nerve damage (neuropathy) is the most important risk factor for ED in people with diabetes. If pelvic nerves that trigger penis muscles to relax are impaired, there may be a break in the chain between brain and penis, disrupting erection. Some researchers suspect that an inadequate supply of oxygen to the nerves causes this damage.


At the same time, people with diabetes are susceptible to a type of blood vessel damage known as endothelial dysfunction. A recent study found that men with ED are at a greater risk of heart disease, which is also associated with endothelial dysfunction. If blood vessels aren't in good working order, the penis may not get enough blood for an erection.
Erectile dysfunction (ED) generally affects men older than 65, but younger men can get it too. If it happens at a younger age, ED may be a warning sign of another health issue. If you have no obvious risk factors and no other health problems, like diabetes, your doctor will run laboratory tests and may order heart tests. The same process that affects the arteries in the penis affects the ones in your heart, too. If something is wrong and it is not diagnosed and treated, you have a fairly high risk over the next four to five years of having some type of cardiac event.
Erectile dysfunction, also known as impotence, is defined as not being able to get or keep an erection firm enough for sex. Remember, occasional erectile dysfunction is not uncommon, but if it’s persistent, erectile dysfunction can be the sign of a more serious health issue, and so you should visit your doctor.Here are 8 surprising causes of erectile dysfunction:High cholesterol. Having a raised cholesterol increases the risk of atherosclerosis where the arteries become narrowed and clogged, resulting in impaired blood flow. When this happens to the arteries in the penis, it can prevent enough blood to create an erection from reaching the penis.Depression. This can cause a lack of interest in sex. See your doctor if this happens to you.Smoking. Smoking causes damage to blood vessels, including those that supply the penis which can result in difficulty in achieving an erection.Cycling. Long hours in the saddle without changing position can cause compression of the perineal nerves and blood vessels, resulting in nerve damage which causes erectile dysfunction. Some saddles are worse than others. If cycling is causing you symptoms of tingling or numbness in your penis, adjust your riding position and take a break.  You might want to look at a different saddle, too. Rodeo riding can have the same effect.Medicines. Erectile dysfunction can be a side-effect of many medicines, including some antipsychotics and antidepressants, cholesterol-lowering medicines, high blood pressure medicines, and epilepsy medicines.Stress. Feelings of stress and anxiety can overflow onto your sex life, and you may find you can’t perform as well as you normally could. 'Performance anxiety' is a common cause of erectile problems.Diabetes. Diabetes raises the risk of erectile dysfunction threefold by its effects on nerves and blood vessels.Peyronie’s disease. This disease causes curvature of the penis due to a hardened area of scar tissue, which results in pain when the man has an erection.If you suffer from erectile dysfunction, don’t be embarrassed – it affects one in 5 men over 40. Remember your doctor can help identify the cause of your erectile dysfunction,  and put you on the path to successful treatment. Read erectile dysfunction – visiting your doctor to find out what to expect when you visit your doctor. Last Reviewed: 18 February 2016
Before a man concludes that oral drugs don’t work for him, he should have his testosterone levels checked to rule out hormone deficiency as the cause of (or as a contributor to) his sexual dysfunction. Other symptoms of low testosterone include a low sex drive and infertility. Checking testosterone levels requires a blood test. If a man’s levels of testosterone are decreased or at the lower end of normal, his doctor may prescribe supplemental testosterone therapy, either as testosterone injections or testosterone gel, which is applied daily to the skin. In some cases, testosterone therapy alone can resolve sexual dysfunction, or it can be combined with the use of oral erectile dysfunction drugs.
What young men should not do is take an ED drug like Viagra without a prescription, or mix them with other drugs. “This is a huge problem and not a safe practice,” says Penny Kaye Jensen, PhD, president of the American Academy of Nurse Practitioners. “Some young men are mixing ED drugs with mind-altering drugs, such as ecstasy or crystal methamphetamine. This is on the rise and is a potentially deadly combination.”
Men with diabetes tend to develop erectile dysfunction 10 to 15 years earlier than men without diabetes. As men with diabetes age, erectile dysfunction becomes even more common. Above the age of 50, the likelihood of having difficulty with an erection occurs in approximately 50% to 60% of men with diabetes. Above age 70, there is about a 95% likelihood of having some difficulty with erectile dysfunction.
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