Men with confirmed hypogonadism — consistently low morning testosterone plus symptoms, often from testicular or pituitary disease — benefit from replacement: improved sexual function, bone density, anaemia correction and modest mood and energy gains, as the NIH-funded TTrials documented in older men with unequivocally low levels. None of the controversy touches this population; the entire debate concerns the vastly larger group of ageing men with borderline levels and nonspecific symptoms to whom the diagnosis was marketed. Endocrine Society guidance is clear that diagnosis requires at least two morning measurements — a standard a striking share of real-world prescribing has never met.

'Low T' was one of the most effective disease-branding campaigns in pharmaceutical history: US testosterone prescribing roughly tripled between 2001 and 2011, driven by direct-to-consumer advertising that converted normal ageing — lower energy, reduced libido, more body fat — into a treatable deficiency. Studies through the boom years found that roughly a quarter of men starting therapy had no recorded testosterone measurement at all, and many more had levels in the normal range. The pattern has now migrated online: direct-to-consumer telehealth platforms prescribe after questionnaires and single afternoon tests, reproducing the 2000s playbook with a subscription model.

The 2015 FDA cardiovascular warning rested on weak observational signals, and the agency demanded a proper trial. TRAVERSE delivered it: 5,246 middle-aged and older men with hypogonadism and elevated cardiovascular risk, randomised to testosterone gel or placebo — no excess in major adverse cardiac events (hazard ratio 0.96). On that basis the FDA revised class labelling in early 2025, removing the broad cardiovascular warning while adding notes on blood-pressure effects and the secondary signals the trial did observe: more atrial fibrillation, acute kidney injury and pulmonary embolism. TRAVERSE answers the question for diagnosed hypogonadal men; it says nothing about enhancement use in men with normal levels.

What remains unsettled is the population marketing created: ageing men with low-normal levels and nonspecific symptoms. Whether they benefit meaningfully, whether years of supraphysiologic dosing through some clinics is safe, and what happens to prostate outcomes over decades of modern prescribing are open questions — TRAVERSE ran under five years in a screened population. The old belief that testosterone causes prostate cancer has softened considerably, but long-horizon surveillance in real-world users, particularly those using doses aimed at gym performance rather than replacement, simply does not exist.

The least-communicated fact in the field: exogenous testosterone suppresses the hormonal axis that drives sperm production, and sustained use can render men azoospermic — sometimes irreversibly after long exposure. Surveys of urologists report steady traffic of young men whose infertility workup reveals prescription testosterone as the cause, frequently started by clinics that never mentioned it. For men who may want children, alternatives that preserve spermatogenesis (clomiphene, hCG) exist, and their omission from a prescribing conversation is a consent failure, not a detail.

Two properly done morning tests before any diagnosis; treat confirmed hypogonadism, ideally through a clinician who will also monitor haematocrit, blood pressure and prostate parameters; and treat TRAVERSE as reassurance for that population rather than a licence for enhancement use. Men considering therapy who may want children need the fertility conversation first. And a testosterone prescription issued after an online questionnaire, without confirmatory testing or fertility counselling, is a commercial transaction wearing clinical dress — the same product the 2000s sold on television, now sold by subscription.