The causes of erectile dysfunction include:
Vascular Disease: Also known as arteriosclerosis, vascular disease is a condition in which the arteries harden and narrow, resulting in a reduction in blood flow throughout the body. The reduction in blood flow to the penis can lead to impotence. Age-related arteriosclerosis is responsible for more than half the cases of impotence in men over 60. Risk factors for arteriosclerosis include diabetes mellitus, high blood pressure, and high cholesterol.
Smoking: Generally considered the biggest risk factor for impotence, smoking is related to arteriosclerosis because smoking reduces blood flow.
Diabetes Mellitus: Damage to small blood vessels and nerves from chronic high levels of blood sugar, which is associated with diabetes mellitus, can impair the transmission of nerve impulses and/or blood flow necessary for erection. Approximately 60 percent of male sufferers of diabetes melitus experience impotence.
Drugs: Impotence is a side effect of drugs that affect the vascular and nervous system. More than 200 prescription drugs, such as drugs for high blood pressure, as well as many over-the-counter medications, fall into this category and can cause impotence.
Hormone Disorders: A deficiency in testosterone can cause impotence. An excess of prolactin, which reduces testosterone, can have the same effect.
Pelvic trauma: Erectile dysfunction can result from surgery of the rectum, colon or prostate; or as a side effect of radiation therapy in that area of the body.
Obesity: Overweight men are more likely to experience erectile dysfunction than thin men.
Metabolic Syndrome: Men with unhealthy cholesterol and triglyceride levels, high blood pressure, belly fat, and insulin resistance are at a higher risk for erectile dysfunction.
Neurologic Conditions: Any condition that results in an interruption of nerve impulses or damage to the nerves from the brain to the penis, including spinal and brain injuries, nerve disorders, multiple sclerosis or Parkinson's disease, may cause impotence.
Prolonged Bicycling: Pressure from a bicycle seat can compress nerves and influence blood flow to the penis, leading to temporary erectile dysfunction and penile numbness. Radiation therapy for prostate or bladder cancer may also damage these nerves.
Peyronie's Disease: An inflammatory condition, peyronie's disease causes scarring of erectile tissue. This can cause curvature of the penis and can interfere with sexual function. Inflammation may also be responsible for pain during erections.
Venous Leak: A venous leak is a leak in the veins of the penis. Because leakage allows blood to leave the penis during erection, an erection is unable to be maintained. Venous leak can occur from damage to the veins in the penis caused by injury or disease.
Psychological Conditions: Emotional states including depression, stress, guilt, worry, anxiety, and low self esteem can lead to a loss of libido and erectile dysfunction. Psychological factors, however, are less relevant than physical causes.
Alcoholism and/or substance abuse
Chronic health conditions: Endocrine system disorders can cause erectile dysfunction