Don’t get swept away by the advertising claims.

For many men, it’s the holy grail: A treatment that promises to beef up their muscles…rev up their sex drive…improve their stamina and concentration…and perhaps even help prevent a heart attack.

So it’s no surprise that prescriptions for testosterone shots, gels and patches have nearly quadrupled over the last decade. About 3% of American men over age 40 now use testosterone therapy.

But is it safe? The answer to this crucial question depends on many factors that aren’t clearly spelled out in the slick advertising—and, in some cases, even by the doctors who prescribe testosterone therapy.

What every man needs to know about testosterone therapy…


Testosterone is manufactured by the body and plays a key role in a man’s health. It helps maintain his bone density…builds his muscles…allows him to produce sperm…and fuels his libido.

A man’s testosterone levels start to decline, however, after age 30—usually by about 1% a year. This is not an illness—it’s a fact of aging. If a man’s testosterone drops farther than normal, though, it can cause fatigue, reduced sex drive, an increase in fat and a decrease in muscle. Some research suggests that low testosterone may also increase a man’s odds of having a heart attack, diabetes and other serious health problems.

No wonder so many men are turning to testosterone therapy, which drug companies are now marketing in successful “low T” ads. The problem is, however, that many doctors are growing increasingly concerned that men whose testosterone levels are simply declining are loading up on the hormone, perhaps to the detriment of their health. Adding to those worries is recent research raising new questions about the safety of testosterone therapy.

Troubling recent finding: In research published in The Journal of the American Medical Association, men using testosterone had nearly a one-third increase in the rate of heart attacks and stroke.

Of course, this research doesn’t prove that testosterone increases cardiovascular risks. Other studies have shown the opposite—that men with higher testosterone may have fewer heart attacks. So what’s going on? It’s possible that the underlying low testosterone, rather than the treatment, was the cause of the increased heart attack risk. It’s also possible that men who start testosterone feel so much better that they overextend themselves and get more exercise—and sex—than their hearts can handle.

For now, there is no clear explanation for the mixed research findings—that’s why it’s so important to use caution when considering testosterone therapy.


Even with these new safety questions, it’s widely agreed that men who meet the clinical criteria for low testosterone need hormone replacement—the benefits outweigh the risks. But what about men whose testosterone levels are waning but do not meet that criteria? That’s where it gets more complicated.

Researchers still argue over what testosterone level is “normal.” When they test men of different ages, they find levels ranging from the low-300s to as high as 1,000 (expressed in nanograms per deciliter—ng/dL—of blood). The cutoff points between “healthy” and “deficient” are somewhat arbitrary. They’re based on averages, not optimal levels.

For now, testosterone replacement is FDA-approved only for men with a clinical deficiency—currently defined as testosterone levels below 300 ng/dL. This condition (hypogonadism) is usually caused by problems in the testicles or the pituitary gland—both play a role in regulating a man’s testosterone levels.


For a reasoned approach to testosterone therapy, here’s my advice…

  • Don’t automatically blame testosterone.
  • The drop in testosterone in older men isn’t caused only by their age. It can be due to chronic diseases, such as high blood pressure and kidney disease. Painkillers can cause it, too. (About three-quarters of men who take long-acting opioids, such as extended-release oxycodone, develop very low testosterone.) Stress is also a factor. Bottom line: Consider using testosterone only after other health problems have been addressed—and corrected.

    Obesity and a sedentary lifestyle are common causes of low testosterone. Overweight men who exercise and lose weight can increase testosterone naturally by up to 25%—in some cases preventing the need for hormone replacement.

  • Take the test.
  • If your doctor has ruled out any physical ailment that may be causing symptoms, get your testosterone level tested (both total and free levels). Low testosterone is easily diagnosed with a blood test. Have the test early in the day, when testosterone levels tend to be highest. If your level is low, ask your doctor to repeat the test on another day, since levels can vary.

  • Get your heart checked out.
  • If your testosterone level is low, don’t start replacement therapy without getting your heart checked out with a stress test, complete blood count (CBC) and tests for cholesterol and high blood pressure. Any cardiac condition that shows up on these tests must be resolved before beginning testosterone therapy.

    Even though the research is not yet definitive, there are enough studies linking testosterone use to heart attack and other cardiovascular problems—especially in men with risk factors for heart disease, including smoking and obesity—that it’s not worth taking a chance on this.

  • Use the right dose.
  • Since a man’s optimal testosterone level is still not clearly defined, I advise a conservative approach. When choosing a dose, I try to get patients’ blood levels within the upper one-fourth of the range generally recommended by endocrinologists—say, about 750 ng/dL—but no higher.

    Different forms of supplemental testosterone are equally effective. Injections are the cheapest, but they must be repeated every 10 to 14 days. Most men learn how to administer the shots themselves.

    Patches are another option, although some men don’t like them, since they can trigger a rash. Testosterone gels and creams are the easiest to use, but they’re expensive—and the medication can transfer to other people through skin-to-skin contact. They’re usually applied to the shoulders or upper arms.

  • Go for checkups.
  • For anyone on testosterone therapy, it’s crucial to get regular checkups. I advise men to get their testosterone levels checked at three months, then every six months. After that, if they’re doing well, they can come in once a year for testing of lipid levels and liver function (testosterone can affect both). I also order tests every six months to monitor a man’s red blood cell (RBC) counts—testosterone increases RBC levels, which can boost his risk for blood clots.

    Other tests you’ll need: A prostate specific antigen (PSA) test to check for prostate cancer every six months. Testosterone replacement doesn’t cause prostate cancer, but it can cause tumors that are already present to grow more rapidly. Men with untreated prostate cancer should not take testosterone. However, testosterone can be given to those who have been successfully treated for prostate cancer. Studies show it does not trigger cancer recurrence.

    In general, men who have low testosterone will feel better within a month after starting testosterone therapy. Optimal testosterone levels should help with weight loss and can boost natural production of the hormone—so many men find that they no longer need treatment.