Erectile dysfunction (ED) can be a total inability to achieve erection for sexual intercourse, an inconsistent ability to do so, or a tendency to sustain only brief erections. The condition affects an estimated 15 million to 30 million American men. However, the broad variations seen with erectile dysfunction make it difficult to define the condition or estimate just how common it really is. Any disorder that causes injury to the nerves or impairs blood flow in the penis can potentially cause erectile dysfunction. Disease, injury, and side effects of drugs are among the things that most often cause it in older men. Some treatment options for erectile dysfunction include drug therapy; psychotherapy; vacuum devices; surgery; and lifestyle changes like losing weight, quitting smoking, and getting more exercise.