Testosterone therapy helps symptomatic men — but most low readings don't need it

Testosterone therapy reliably does one thing in men who genuinely lack the hormone: it modestly improves sexual function. The largest randomised trials now also suggest it does not, over a few years, raise the risk of heart attack or stroke in the high-risk men most likely to be prescribed it [s1][s2]. What it is not is a general tonic for ageing, low energy or a single below-range blood test — and the men who benefit are a narrower group than the marketing implies [s3].

What the therapy actually delivers

The cleanest read on benefit comes from the Testosterone Trials, which randomised 790 men aged 65 or older, all with a serum testosterone below 275 ng per deciliter and symptoms of hormone deficiency, to a year of testosterone gel or placebo [s2]. Raising testosterone into the mid-normal range of young men significantly increased sexual activity (P<0.001), along with sexual desire and erectile function [s2]. The effects elsewhere were slim: there was no significant benefit for vitality, and the proportion of men who walked at least 50 metres further split 20.5% on testosterone versus 12.6% on placebo only when all participants were pooled [s2]. Mood and depressive symptoms were slightly better [s2]. In short: a moderate sexual benefit, a small lift in mood, and little else.

Is it safe for the heart?

The long-running worry was cardiovascular. TRAVERSE, the trial regulators demanded, addressed it directly: 5,246 men aged 45 to 80 with existing or high risk of cardiovascular disease, symptoms of hypogonadism and two fasting testosterone levels below 300 ng per deciliter, randomised to testosterone gel or placebo [s1]. Over a mean follow-up of 33.0 months, a major cardiac event — cardiovascular death, non-fatal heart attack or non-fatal stroke — occurred in 182 men (7.0%) on testosterone and 190 (7.3%) on placebo, a hazard ratio of 0.96 that met the trial's bar for non-inferiority [s1]. The secondary endpoint, which also counted coronary procedures, showed the same broad parity [s1]. That is reassuring, but not a clean bill of health: the testosterone group had more atrial fibrillation, more acute kidney injury and more pulmonary embolism [s1]. And a follow-up of 33 months cannot rule out slower harms, so the result answers the specific question of short-to-medium-term heart safety rather than declaring the drug risk-free. The trial was funded by AbbVie, which sells the gel [s1].

Who actually needs it

Here the honest answer diverges from the clinic pitch. The Endocrine Society's guideline recommends diagnosing hypogonadism only in men who have both symptoms and unequivocally and consistently low testosterone — a fasting morning total testosterone, confirmed by repeating the measurement, not a single afternoon draw [s3]. It recommends against starting therapy in men planning fertility in the near term, or with breast or prostate cancer, a palpable prostate nodule, a PSA above 4 ng/mL, untreated severe sleep apnoea, uncontrolled heart failure, or a heart attack or stroke in the previous six months [s3]. When treatment is warranted, the target is the mid-normal range, not supraphysiological levels [s3].

Two things follow. A low reading in a man with no symptoms is not a diagnosis. And testosterone therapy suppresses sperm production, which is why the guideline flags fertility — a trade-off covered in more depth in testosterone therapy and male fertility [s3].

What it means for a reader

Testosterone works for the problem it was studied on — symptomatic deficiency, confirmed properly, mainly showing up as flagging sexual function. For that man the evidence now supports a real if moderate benefit and, over a few years, an acceptable cardiovascular profile [s1][s2]. It is not a treatment for the tiredness, low mood or thinning muscle of ordinary ageing, and it is not something to start on the strength of one borderline result — the same logic that applies when short sleep or carried weight temporarily depresses the number.

The commercial pressure runs the other way. Direct-to-consumer testosterone clinics are built to read a single low value as a lifelong prescription, and the guideline's careful diagnostic gate — symptoms plus two confirmed low morning readings — exists precisely to stop that [s3]. If a man has genuine symptoms, the test worth having is a proper one, repeated. If he does not, no number on a panel is a reason to start.