Starting Testosterone Therapy

Testosterone therapy is one of the more consequential things a generally healthy adult can start, and it is the one most commonly begun on the thinnest evaluation. The gap between how carefully it should be approached and how casually it often is sold is the reason this guide is long.

The diagnosis comes before the decision

Hypogonadism is a clinical diagnosis, not a lab value. It requires consistently low testosterone and symptoms consistent with deficiency. Either alone is insufficient, and the reason is that both are unreliable in isolation. Symptoms — fatigue, low mood, reduced libido, poor concentration, loss of strength — overlap almost entirely with poor sleep, depression, thyroid disease, anaemia, and simply being under-recovered. Many people who feel exactly as described have normal testosterone and something else going on. Levels, meanwhile, move. Testosterone follows a diurnal rhythm and is highest in the morning. It falls during acute illness, after several nights of poor sleep, during significant caloric restriction, and with obesity and obstructive sleep apnoea. This is why guidelines call for at least two morning measurements on separate days before a diagnosis is made.

Primary or secondary

Once low testosterone is established, the next question is where the problem is. Primary hypogonadism means the testes are not producing adequately. LH and FSH are typically elevated, because the pituitary is signalling harder to compensate. Secondary hypogonadism means the signal from the pituitary is inadequate. LH and FSH are low or inappropriately normal for a low testosterone. The distinction changes the workup and the options. Secondary hypogonadism raises questions the answers to which may be reversible — obesity, sleep apnoea, opioid use, excess alcohol, anabolic steroid use, and, less commonly, a pituitary lesion, which is why prolactin is usually checked. A service that goes straight from a low reading to a prescription without asking why it is low has skipped the part that matters most.

Fertility is the question to raise first

Exogenous testosterone suppresses LH and FSH, and with them sperm production. For some men this becomes profound, and recovery after stopping is not always complete, and not always quick. If there is any chance you will want to conceive, say so before you start. It changes the approach entirely — it may point toward agents that work through your own axis rather than replacing the hormone from outside, or toward preserving a semen sample first. It is far easier to plan for this at the beginning than to unwind it later.

Why telehealth works differently here

Testosterone is a Schedule III controlled substance in the United States. Two things follow. First, prescribing requires a synchronous consultation — a live video visit with a clinician, not a questionnaire reviewed asynchronously. Any service offering testosterone on the strength of a form alone is operating outside the rules. Second, the federal framework permitting telehealth prescribing of controlled substances without a prior in-person examination has been running under temporary flexibilities that are currently extended to the end of 2026. Permanent rules have been proposed and not finalised. Anyone starting therapy by telehealth should understand that the regulatory pathway they are using has an expiry date on it as things stand.

Routes of administration

Intramuscular or subcutaneous injection, typically weekly or twice weekly. Twice-weekly dosing produces smaller peaks and troughs. Subcutaneous administration with a small needle has become common and is generally better tolerated than the older intramuscular approach. Transdermal gels and creams, applied daily. Steadier levels, but absorption varies between people, and there is a genuine risk of transferring testosterone to a partner or child through skin contact — which requires real discipline about application sites and covering them. Pellets, implanted subcutaneously and releasing over months. Convenient, and irreversible for the duration: if the dose is wrong, it cannot be adjusted until it wears off. There is no universally superior route. The trade-offs are between steadiness, adjustability, transfer risk and how much you want to think about it.

Monitoring is the therapy

The single most important difference between well-run and badly-run testosterone therapy is monitoring. Haematocrit is the one that catches people out. Testosterone stimulates red cell production, and haematocrit can climb well above the normal range without producing any symptom you would notice. It is tracked with bloodwork for that reason. If it rises too far, the response is to reduce the dose, lengthen the interval, or pause — and in some cases to remove blood. PSA is monitored where age-appropriate, on the understanding that testosterone therapy is not recommended in the presence of untreated prostate cancer. Oestradiol rises with testosterone, because some of it is converted. This is normal and largely desirable — oestradiol matters for bone density, lipids and libido in men. Reflexively suppressing it with an aromatase inhibitor is a common error in poorly supervised programmes and creates its own problems. Lipids, liver function, and blood pressure are followed as part of the general picture. A programme that prescribes and then does not look again is not managing anything.

What to settle before you start

• Have I had at least two morning testosterone measurements on separate days?
• Do I know whether this is primary or secondary, and if secondary, has the reason been looked for?
• Has sleep apnoea been considered?
• Do I have a fertility plan?
• What is the monitoring schedule, and what happens if haematocrit rises?
• Who reviews my results, and how do I reach them?
• What does this cost in total, including the bloodwork, and what happens if I stop?

Therapy for genuine hypogonadism is generally long term, because stopping returns you to where you started and the recovery of your own production is not immediate. That is not a reason to avoid it. It is a reason to be sure of the diagnosis first.