Testosterone therapy is no fountain of youth for older men, though it might help some who are impotent.

That’s according to new guidelines from the American College of Physicians — the first from the group to address the issue of treating age-related “low T.”

It’s known that men’s testosterone levels decline with age. And for years industry has promoted the idea that men suffer a range of symptoms caused by what’s sometimes described as “male menopause.” The list includes fatigue, weakness, muscle loss, dulled memory and thinking, depression, and dampened libido and erectile dysfunction.

Yet for nearly all of those problems, there is no good evidence testosterone therapy helps, the college found in a research review.

The only area where there is some benefit, the group says, is in treating sexual dysfunction. On average, studies have found “small improvements” in sexual and erectile function.

The lackluster performance in clinical trials is “a bit surprising,” said ACP president Dr. Robert McLean. But, he pointed out, the fact that testosterone wanes with age does not automatically mean that’s behind men’s health issues. And that means replacing testosterone will not necessarily help.

That never stopped manufacturers of supplemental testosterone, however. For years, they launched aggressive marketing campaigns warning men of the health effects of age-related declines of the male hormone.

Between 2009 and 2013, the number of U.S. men on testosterone shot up from 1.3 million to 2.3 million, according to the U.S. Food and Drug Administration. And most, the agency said, were not using it for an established indication — namely, certain medical conditions that cause testosterone deficiency.

Instead, they were using it to counter the aging process.

The tide has turned in more recent years. One study found that Americans’ testosterone use dropped substantially between 2013 and 2016 after questions were raised about the risks of heart disease or prostate cancer.

“The enthusiasm for it is less than it used to be,” said Dr. Victor Adlin, an endocrinologist from the Lewis Katz School of Medicine at Temple University in Philadelphia.

Still, it remains something men ask about, Adlin said. He wrote an editorial published with the guidelines Jan. 7 in the Annals of Internal Medicine.

Two other medical groups — the Endocrine Society and the American Urological Association — have guidelines on treating age-related low testosterone, Adlin said. And they agree with the ACP on the central point: Testosterone might help some men with sexual dysfunction, but it should not be prescribed for vague symptoms like fatigue and low energy.

The ACP recommends trying injection testosterone over patches or other skin preparations. Both methods are similarly effective, McLean said, but injection therapy is far cheaper: $156 per year, versus $2,135, based on Medicare claims.

As for safety, the overall evidence from 20 studies suggests that testosterone does not raise the risks of heart problems, blood clots or prostate cancer, McLean said. Those studies followed men for up to 10 years, he added, so it’s not possible to say what the risks are beyond that.

How can men with sexual dysfunction know if they do, in fact, have low testosterone? Blood levels of the hormone should be measured on two separate days to confirm the results, Adlin said. And both should be done in the morning, he added. Testosterone levels fluctuate and are typically highest early in the day.

“If you have confirmed low levels, and your sexual symptoms are bothersome enough to need treatment, it’s reasonable to start testosterone,” Adlin said. “But don’t start it and forget it.”

The ACP says men should have their symptoms reevaluated within a year — and if they are not better, stop using testosterone. Adlin said the six-month mark can be a good time for that check-in.

Low testosterone is very common among older men, according to the ACP. It’s seen in 20% of U.S. men over age 60, 30% of those over age 70, and half of men older than 80.

But based on the evidence, only select men will gain any benefit from taking testosterone.

“It is not a fountain of youth,” McLean said.

More information

The American Urological Association has more on low testosterone.