Erectile dysfunction affects approximately 15 to 30 million men in the United States. It is defined as the inability to get or keep an erection that's firm enough for intercourse. This is not to be confused with the occasional erection issues. "The 'sometimes things don't work out' kind of scenario happens to all guys, across the age spectrum and that shouldn't be a point of stress," says Benjamin N. Breyer, assistant professor in the department of urology at University of California, San Francisco and interim chief of urology at San Francisco General. "But if it happens consistently and it's bothersome to the patient or the partner, the guy should seek help." The chances that a man will experience erectile dysfunction increase as he gets older but it's not inevitable. In most cases, if it does occur, it's relatively easy to address, usually with medication. There are also several preventative steps men can take to lessen their chances of developing erectile dysfunction.