It is not clear whether aging itself or the disorders associated with aging cause the gradual changes that occur in men's sexual functioning. The frequency, duration, and rigidity of erections gradually decline as men age. Levels of the male sex hormone (testosterone) tend to decrease, reducing sex drive (libido). Blood flow to the penis decreases. Other changes include decreases in penile sensitivity and ejaculatory volume, reduced forewarning of ejaculation, orgasm without ejaculation, more rapid detumescence, and a longer refractory period.
Last full review/revision February 2013 by Irvin H. Hirsch, MD