What is testosterone therapy for men?

What it is

Testosterone therapy supplies testosterone, the main male sex hormone, to men whose testicles make too little, a condition called hypogonadism. FDA-approved products are labeled for two kinds. In primary hypogonadism the testicles themselves fail, for example after chemotherapy or because of Klinefelter syndrome, a chromosome condition. In secondary hypogonadism the pituitary gland or the hypothalamus, a brain region above it, fails to signal them, for example because of a tumor or injury. Some older labels also cover delayed puberty in boys.^1,2,3

The FDA says no testosterone product is approved for men whose low testosterone has no associated medical condition. Labels add that safety and effectiveness in age-related low testosterone have not been established. One injectable form is also approved for some women with advanced breast cancer.^4,1,2

How low testosterone is diagnosed

The Endocrine Society’s 2018 guideline recommends diagnosing hypogonadism only in men with symptoms and signs of deficiency and clearly, consistently low blood levels, confirmed by repeating a fasting morning test. Testosterone labels likewise ask for low readings on at least two separate mornings.^7,1

It also recommends measuring two pituitary hormones, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), to tell the two kinds apart, and advises against screening men in general. For men 65 or older with symptoms and consistently low morning levels, it suggests deciding case by case, after discussing risks and benefits.⁸

It recommends against starting testosterone in men planning to father a child soon, or in men with any of these:⁷

A 2020 American College of Physicians guideline on age-related low testosterone suggests discussing treatment with men who have sexual problems and want them improved. It suggests stopping if sexual function has not improved within 12 months, and not starting testosterone for energy, physical function or thinking. It rates its evidence as low certainty.⁹

How it works

The testicles make testosterone when the pituitary gland releases LH. Testosterone inside the testicles is normally far higher than in blood, and researchers think sperm production depends on that high level, along with FSH. Testosterone taken as a drug makes the pituitary release less LH and FSH, so testosterone inside the testicles falls.^1,10

How it is taken

What the research in people shows

The gel later used in TRAVERSE was tested for approval in a 182-day trial of 274 men that measured blood testosterone, not symptoms.¹

After a 2014 advisory meeting on reports of strokes, heart attacks and deaths in men using testosterone, the FDA recommended a large safety trial in men with age-related low testosterone. TRAVERSE, published in 2023, randomly assigned 5,246 men aged 45 to 80 with low testosterone, symptoms, and heart disease or high heart risk to testosterone or placebo gel. Treatment averaged about 22 months, and follow-up about 33. AbbVie and others funded it.^19,4,20,1

Heart attacks, strokes and cardiovascular deaths were similar in the two groups, meeting the trial’s test of being no worse than placebo; it was not designed to show testosterone was better.^20,1

TRAVERSE excluded men at high prostate cancer risk. Prostate cancers, including high-grade ones, were uncommon in both groups, and the small difference could have been chance. PSA rose more with testosterone.²¹

Studies within TRAVERSE looked at other outcomes. Among 1,161 men with low sex drive, testosterone improved sexual activity and desire more than placebo, but not erections. Across all 5,204 men analyzed, mood and energy improved slightly more with testosterone; thinking and sleep did not. Of 815 men with anemia, a shortage of red blood cells, more on testosterone saw it corrected. In 1,175 men with prediabetes, testosterone did not slow progression to diabetes.^22,23,24,25

The T4DM trial, published in 2021, gave 1,007 Australian men aged 50 to 74 a lifestyle program plus testosterone or placebo injections for 2 years. All had prediabetes or new type 2 diabetes, and low or low-normal testosterone without testicular or pituitary disease. Fewer on testosterone had type 2 diabetes at 2 years.²⁶

The Testosterone Trials, published in 2016, gave 790 men 65 or older a year of testosterone or placebo gel. All had low testosterone and symptoms, with no known cause other than age. The National Institutes of Health funded them, with funding and gels from AbbVie. Testosterone moderately improved sexual function and slightly improved mood, but not energy or walking distance. The authors said the trials were too small to judge risks.²⁷

In smaller studies within them, bone density rose more with testosterone in 211 men, and soft (noncalcified) plaque in the heart arteries grew more on testosterone in 170 men given heart scans.^28,29

Side effects and risks

Two kinds of product carry a boxed warning at the top of the label. On gels and solutions, it warns that children who touched skin where a man applied testosterone developed male sexual traits (virilization), such as an enlarged penis or clitoris and pubic hair. In a few children, genital size and bone age did not fully return to normal after exposure stopped. Exposed women can develop more body hair and acne, and testosterone can harm a female fetus. Gels and solutions are also flammable until dry.^1,14

On long-acting undecanoate injections, the boxed warning covers oil droplets reaching the lungs (pulmonary oil microembolism) and severe allergic reactions (anaphylaxis). These can follow any injection, so patients are watched for 30 minutes after each.¹³

Beyond the boxed warnings, testosterone labels warn about the following risks, some only for particular forms:

Because testosterone can lower sperm production, some men use other drugs with it or instead of it. They include human chorionic gonadotropin (hCG), an injected hormone that stimulates the testicles, and enclomiphene and clomiphene, pills taken to make the body produce more of its own testosterone. Of these, only hCG is FDA-approved for low testosterone, in some men whose pituitary fails; the journal’s article on these drugs covers their evidence, risks and FDA status.^1,5,6,40

FDA status

Testosterone is FDA-approved for the conditions above. In February 2025 the FDA asked makers to add TRAVERSE results to all testosterone labels and to remove boxed-warning language on cardiovascular risk. It kept the label statement on age-related low testosterone and required a blood pressure warning on every product. The autoinjector and the capsules taken by mouth then dropped their boxed warnings on blood pressure.^19,12,16

In April 2026 the FDA said a preliminary review of published trials pointed to a possible new use: low sex drive in men whose low testosterone has no known cause. It invited makers of approved products to discuss applying for that use. No label included it as of November 13, 2026.^30,1,16

In June 2026 the FDA asked makers to remove the label statement on age-related low testosterone and to revise warnings on prostate cancer and enlarged prostate (benign prostatic hyperplasia). Labels still carried the older wording on November 13, 2026.^4,11,16

Compounded testosterone, in any form, is not FDA-approved, so the FDA does not verify its safety, effectiveness or quality before sale. The FDA says compounded drugs should be used only when an approved drug cannot meet a patient’s needs. It warns that poor compounding can cause contamination or the wrong amount of active ingredient, which can lead to serious injury and death.¹⁸

Federal law also bars a 503A pharmacy (a state-licensed pharmacy that compounds under section 503A) from compounding essentially copies of a commercially available drug regularly or in inordinate amounts.³¹

Controlled substance, telehealth and sport rules

Testosterone is a Schedule III controlled substance, listed among the anabolic steroids. A Schedule III prescription cannot be filled more than six months after it is written or refilled more than five times.^32,33

Under a temporary rule from the Drug Enforcement Administration (DEA), a registered clinician may prescribe testosterone after a live video visit, without an in-person exam, through December 31, 2026. State law may add limits, and the journal’s license-checking article explains the rule’s conditions and what happens if it lapses.^34,35

For tested athletes, the World Anti-Doping Agency’s 2026 and 2027 Prohibited Lists ban testosterone at all times, in and out of competition.^36,37

What isn’t known

TRAVERSE treated men for about 22 months on average, and about 61 in 100 stopped early, so effects over many years, including on prostate cancer, are unknown. It tested only a daily gel, so it does not show whether injections carry the same heart risks. It also studied men 45 to 80 at high heart risk, not younger, healthier men.^20,1

A 2026 randomized trial gave testosterone or placebo injections for 12 weeks to 136 men whose low-grade prostate cancer had been removed by surgery. None had signs of the cancer returning, but its authors wrote that the trial was too small and short to judge recurrence or long-term safety.³⁸

Higher bone density in the Testosterone Trials did not mean fewer fractures: in TRAVERSE, fractures were more common with testosterone. The plaque study saw no heart attacks or strokes in either group, so what the extra plaque means is unknown.^28,39,29

Questions to ask a clinician