Erectile dysfunction (also known as ED or impotence) can take several forms, including a total inability to achieve erection for sexual intercourse, an inconsistent ability to do so, or a tendency to sustain only brief erections. An estimated 15 million to 30 million American men experience erectile dysfunction. However, the condition's broad variations make it difficult to define it or estimate how prevalent it is. In older men, the cause is usually something physical like disease, injury, or side effects of drugs. A few of the drugs that have been licensed to treat erectile dysfunction include Viagra^®, Levitra^®, and Cialis^®. Also, research on new drugs for treating erectile dysfunction is expanding rapidly -- patients should ask their healthcare providers about the latest advances in treatment options. In addition to medications, other forms of erectile dysfunction treatment include counseling, vacuum devices, lifestyle changes (like losing weight, quitting smoking, and exercising more) and in some cases, surgery.