Impotence may have a physical, lifestyle, or psychological cause. An underlying medical condition is the most common cause of impotence. Such conditions may interfere with the blood supply to the penis, the generation of nerve impulses involved in getting and maintaining an erection.

Some medical conditions that commonly cause impotence include diabetes, cardiovascular disease, atherosclerosis, or the hardening of the arteries, kidney disease, and diseases affecting the nervous system. Diabetes causes damage to both blood vessels and nerves. Cardiovascular and other vascular diseases reduce the flow of blood to the penis, and the veins that remove blood from the engorged penis may be leaky. Kidney disease may cause impotence through chemical changes that affect circulating hormones, blood supply, nerves and overall energy. Conditions that affect the brain or nerves, such as stroke, Alzheimer