A dizzying number of factors can conspire against sexual desire as midlife approaches: depression, medications, illness, career worries, financial pressures, marriage troubles, young children in the home (or an empty nest), the sense that life is half over … and then there's testosterone.
Usually we think of testosterone as a hormone that men have — in abundance. But testosterone plays a big role in setting the pace for a woman's sex drive as well. And both men and women experience a natural drop in testosterone that can cause libido to ebb in midlife.
Testosterone levels peak in the mid-20s for both men and women. For women, who have about 1/10 to 1/20 the amount of testosterone that men have, testosterone levels taper off slowly until they plateau around the age of 45. For men, testosterone levels continue to wane into their 70s.
By the time women reach menopause, their testosterone levels are about half of what they were in their 20s. Men's testosterone levels decrease by about 1% per year and then drop faster as they approach older age.
Testosterone treatment for men and women can help restore the hormone to a level that will push the sexual accelerator. But how often you feel like jumping in the sack is tied to so many complex biological and lifestyle factors, experts say, that it's important to make sure you're treating the appropriate issues. If you have a serious illness or depression, those should be addressed separately.
And a number of things can go wrong with testosterone treatment.
"Testosterone use is very widespread, but it's misused a lot," says Dr. Glenn Braunstein, an endocrinologist and chairman of the department of medicine at Cedars-Sinai Medical Center in Los Angeles.
Inaccurate diagnoses can result simply because blood draws were done at the wrong time of day. In men, testosterone levels peak in the morning and dip in the afternoon, so if doctors rely on a single blood test done in the afternoon, they may misdiagnose the source of the problem, Braunstein says.
Men have a number of options for treating low testosterone, including the topical gels Testim and AndroGel. These prescription drugs deliver the hormone from the skin into the bloodstream. Testosterone patches and injections are also available.
The well-known Viagra and its counterparts, on the other hand, don't have any effect on libido; rather, they improve erectile function. Getting and maintaining an erection requires generation of nitric oxide, which aids in engorgement of blood vessels. But when nitric oxide levels drop too quickly, the erection is lost. Viagra, which is made only for men, inhibits the breakdown of nitric oxide to keep an erection from waning prematurely.
Patients whose testosterone levels are low may not benefit fully from taking Viagra until levels of the key hormone are increased, Braunstein says. Yet in some cases, testosterone can help both libido and erectile function, though it's not entirely clear why that is so.
"The observation has been that you may not get an adequate response to Viagra unless you add testosterone back," Braunstein says. But, he notes, "we do not want men who are otherwise normal in regards to testosterone to run out and get it because they want a better effect from Viagra."
The Food and Drug Administration has not approved any testosterone treatments for women, though a topical gel, called LibiGel, is in advanced clinical trials.
To fill the void, doctors sometimes resort to prescribing off-label treatments for women, such as low doses of the gels approved for men, says Sheryl Kingsberg, a clinical psychologist and chief of obstetrics/gynecology behavioral medicine at University Hospitals Case Medical Center in Cleveland.
But Kingsberg emphasizes that other factors — such as exercise, fatigue, sleep deprivation, stress, cardiovascular disease and obesity — cannot be overlooked when trying to restore, or maintain, sex drive. "All of those things absolutely affect overall health and sexual health," she says.
The converse is true as well. Studies show that having a healthy sex life can improve health and well-being. And for women who reach menopause and assume their best days are behind them, Kingsberg has two words: No way.
"It's important for post-menopausal women to know that the quality of a relationship has been shown to be a much better predictor of sexual health and sexual satisfaction than age and menopausal status," she says.
And another reason to keep one's libido in good working order: Without it, a relationship can really suffer, she says. "Bad sex does way more to subvert an otherwise good relationship than good sex does to promote an average one."