The American Academy of Family Physicians says the condition doesn't have to be a natural part of getting older. ED often is attributed to physical or psychological causes. Physical reasons may include:

• Having a side effect of surgery on the prostate or bladder, or radiation therapy to the testicles.
• Having low testosterone levels, kidney failure, liver failure, multiple sclerosis or Parkinson's disease.
• Having chronic conditions such as diabetes, high blood pressure, or hardening of the arteries.
• Having had a stroke or an injury to the brain or spinal cord.
• Using too much tobacco or alcohol.
• Being tired.

-- Diana Kohnle