Life Cycle of a Penis

Experts explain how a penis changes in size, appearance, and sexual function with age.

From the WebMD Archives

It's no secret that a man's sexual function declines with age. As his testosterone level falls, it takes more to arouse him. Once aroused, he takes longer to get an erection and to achieve orgasm and, following orgasm, to become aroused again. Age brings marked declines in semen volume and sperm quality. Erectile dysfunction (ED), or impotence, is clearly linked to advancing years; studies show that between the ages of 40 and 70, the percentage of potent men falls from 60% to roughly 30%.

Men also experience a gradual decline in urinary function. A man's urine stream weakens over time as a consequence of weakened bladder muscles and, in many cases, prostate enlargement.

And that's not all. Recent research confirms what men have long suspected and, in some cases, feared. The penis itself undergoes significant changes as a man moves from his sexual prime -- around age 30 for most guys -- into middle age and on to older age. Changes include:

Appearance. There are two major changes. The head of the penis (glans) gradually loses its purplish color, the result of reduced blood flow. And there is a slow loss of pubic hair. "As testosterone wanes, the penis gradually reverts to its prepubertal, mostly hairless, state," says Irwin Goldstein, MD, director of sexual medicine at Alvarado Hospital in San Diego and editor-in-chief of The Journal of Sexual Medicine.

Penis Size. Weight gain is common as men grow older. As fat accumulates on the lower abdomen, the apparent size of the penis changes. Ira Sharlip, MD, clinical professor of urology at the University of California, San Francisco, says, "A large prepubic fat pad makes the penile shaft look shorter."

"In some cases, abdominal fat all but buries the penis," says Ronald Tamler, MD, PhD, co-director of the Men's Health Program at Mount Sinai Hospital in New York City. "One way I motivate my overweight patients is by telling them that they can appear to gain up to an inch in size simply by losing weight."

In addition to this apparent shrinkage (which is reversible) the penis tends to undergo an actual (and irreversible) reduction in size. The reduction -- in both length and thickness -- typically isn't dramatic but may be noticeable. "If a man's erect penis is 6 inches long when he is in his 30s, it might be 5 or 5-and-a-half inches when he reaches his 60s or 70s," Goldstein says.

Continued

What causes the penis to shrink? At least two mechanisms are involved. One is the slow deposit of fatty substances (plaques) inside tiny arteries in the penis, which impairs blood flow to the organ. This process, known as atherosclerosis, is the same one that contributes to blockages inside the coronary arteries -- a leading cause of heart attack.

Goldstein explains that another mechanism involves the gradual buildup of relatively inelastic collagen (scar tissue) within the stretchy fibrous sheath that surrounds the erection chambers. Erections occur when these chambers fill with blood. Blockages within the penile arteries -- and increasingly inelastic chambers -- mean smaller erections.

As penis size changes, so does the size of the testicles. "Starting around age 40, the testicles definitely begin to shrink," Goldstein says. The testicles of a 30-year-old man might measure 3 centimeters in diameter, he says; those of a 60-year-old, perhaps measures only 2 centimeters.

Curvature. If penile scar tissue accumulates unevenly, the penis can become curved. This condition, known as Peyronie's disease, occurs most commonly in middle age. It can cause painful erections and make intercourse difficult. The condition may require surgery.

Sensitivity. Numerous studies have shown that the penis becomes less sensitive over time. This can make it hard to achieve an erection and to have an orgasm. Whether it renders orgasm less pleasurable is still an open question.

Experts say these changes need not ruin your erotic life. One recent study showed significant declines in erectile function, libido, and ejaculatory function in the men studied but only moderate decreases in sexual satisfaction. The study's authors concluded that, "Older men may be less likely to perceive these declines as a problem and be dissatisfied."

As Goldstein puts it, "The most important ingredient for a satisfying sex life is the ability to satisfy your partner. And that doesn't require peak sexual performance or a big penis."

WebMD Feature Reviewed by Louise Chang, MD on December 05, 2011

Sources

SOURCES:

Ira Goldstein, director of sexual medicine, Alvarado Hospital, San Diego; editor-in-chief, The Journal of Sexual Medicine.

Fertility and Sterility, February 2001.

Journal of Sexual Medicine, May 2008.

Ira Sharlip, MD, clinical professor of urology, University of California, San Francisco.

Ronald Tamler, MD, PhD, co-director, Men's Health Program, Mount Sinai Hospital, New York City.

McCullough, A. Reviews in Urology, May 2003.

National Kidney and Urologic Diseases Information Clearinghouse web site: "Peyronie's Disease."

Rowland, D.L. Archives of Sexual Behavior, February 1989.

Rowland, D.L. Archives of Sexual Behavior, December 1993.

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