Put 25 men in their 60s in a room, and odds are one is taking testosterone. Between 2011 and 2013, the number of American men prescribed the male hormone nearly doubled, from 1.3 to 2.3 million men.

Yet we still know so little about this huge human experiment. It’s true that levels decline with age, which might contribute to  low sex drive, muscle weakness, fatigue and depressed mood. But does taking testosterone really help? Is it safe? Or is it an ineffective, perhaps even dangerous fad created by a massive advertising campaign—to “treat” normal aging in men?

The best way to find out—careful medical studies. Now there is one. It doesn’t answer all the questions, but it does identify the benefits—modest though they are—for a specific group of men.

Are you, or is someone you know, one of them?


The new study homes in on men 65 and older with clinically low blood testosterone levels (less than 275 nanograms per deciliter) and symptoms, such as low libido/sexual function, difficulty walking or inability to walk at a normal pace (faster than 2.7 miles per hour for six minutes) or low vitality such as fatigue. It’s the first large double-blind, placebo-controlled study—the gold standard—to study testosterone-replacement therapy in older men.

Even before the study got going, there was a significant finding. Most of the men who volunteered for the study didn’t actually have low testosterone. When their blood was tested, only 1.5% actually qualified for inclusion. This is in line with other studies that find that many men being treated for “low T” don’t have it—many don’t even get tested. In this study, men who qualified got either topical testosterone gel—enough to raise their levels to the average for a man in his 20s or 30s—or a placebo gel. Results…

• Sexual function improved—modestly. On a scale of 0 to12, scores for sexual activity went from 1.4 to 1.6 for the testosterone group, with no improvement for the placebo group. On a scale of 0 to 33, sexual desire improved from 11.9 to 14.15 for the testosterone group, while the placebo group showed no improvement. And increased erectile function went up only 3.1 points on a scale of 0 to 30—from 8.0 to 11.1—among those who got the testosterone.

• Mood improved and depressive symptoms went down—slightly.

• There was no improvement in vitality or the ability to walk more easily or more briskly.


One big question that the study didn’t answer—is testosterone therapy safe? It’s still a muddy issue. There is concern that testosterone therapy may increase the long-term risk for prostate cancer, for example. Some studies have also shown that using testosterone might increase the risk for cardiovascular disease, while others have found no risk or even a protective effect. To be prudent, the study excluded men with significant symptoms of prostate enlargement and those at high risk for either prostate cancer or heart disease. In this short-term study of testosterone (one year of therapy), there were no serious adverse effects. But we’ll need more research to fully answer the safety questions.

Also, this study does not shed any light on whether middle-aged men, who are the biggest consumers of testosterone, would benefit…or whether men with slightly higher levels than the study cut-off might improve, too. But it does find that there is a small group of older men for whom this may be an appropriate treatment. Just don’t expect the world.

“On average, the effects are generally small, and it’s not clear that they are clinically important,” says Eric Orwoll, MD, in the department of medicine at Oregon Health and Science University in Portland, who wrote an accompanying editorial to the study. “It may be that the benefits of testosterone are more important in some men than others. Right now, however, there’s no way to predict just who will benefit the most—or the least.”


As a practicing physician, Orwoll would consider prescribing testosterone to men who fit the criteria of the study, have relevant symptoms and who want to give it a try.  He usually prescribes a trial period of, say, three to six months to see if there is benefit.

So if you do feel your sex drive has diminished, talk to your doctor about getting tested for testosterone to see if it is low and to rule out other causes of your symptoms such as depression, stress, heart conditions and sleep apnea. Your doctor should also rule out any reasons not to take testosterone, such as high risk for heart disease or prostate cancer.

Whatever you choose, it’s also important to realize that there are many ways to boost your testosterone level without drugs—such as by losing weight. To learn more tips, see Bottom Line’s article “Low Testosterone: Is It Overtreated?” And don’t forget to eat more blueberries.