Erectile dysfunction (ED), the inability to achieve or sustain an erection, is often the result of disease, injury, or a side effect of certain drugs, including blood pressure drugs, antihistamines, antidepressants, tranquilizers, appetite suppressants, and cimetidine (an ulcer drug). Damage to nerves, arteries, smooth muscles, and fibrous tissues of the penis are the most common causes of erectile dysfunction. Diabetes, kidney disease, chronic alcoholism, multiple sclerosis, atherosclerosis, vascular disease, and neurologic disease account for about 70 percent of ED cases. Treatment may include lifestyle changes, adjusting medications to alleviate side effects, medications to induce erection, and surgery.