Erectile dysfunction (also known as ED or impotence) can be a total inability to achieve erection for sexual intercourse. It can also be an inconsistent ability to do so, or a tendency to sustain only brief erections. Erectile dysfunction becomes more common as men get older -- roughly 5 percent of 40-year-old men and between 15 percent and 25 percent of 65-year-old men experience the condition. However, because erectile dysfunction can appear in different forms, it is difficult to define it or estimate precisely how common it is. In older men, erectile dysfunction is often caused by something physical like disease, injury, or side effects of drugs. Fortunately, drugs like Viagra^®, Levitra^®, and Cialis^® have been licensed to treat this condition. Other treatment options include counseling, implanted devices, and lifestyle changes (such as losing excess weight and quitting smoking). In rare cases, surgery may even be considered.