TRT explained honestly: who it helps, what it costs, what to ask

Testosterone replacement therapy is a legitimate treatment for a specific diagnosis. It is also the product an entire online industry sells to men who do not have that diagnosis, in language borrowed from performance marketing, not medicine.

Both things are true at once, which is why this guide separates them. Here is what TRT does when it is the right treatment, what the largest trials show it does not do, what it costs you beyond money, and how to tell a careful clinic from a subscription mill.

Who it is actually for

The entry requirement is not a feeling. Entry requires compatible symptoms or signs plus consistently low testosterone, confirmed on at least two early-morning fasting tests.

Urology guidance treats anything under 300 ng/dL as low enough to support the diagnosis, and makes that diagnosis only when the low level comes with symptoms or signs (AUA guideline). The Endocrine Society won't commit to one universal number; what it demands instead is unequivocally and consistently low concentrations, measured on an accurate assay with an appropriate reference range (JCEM, 2018). Its 2026 statement doubles down on repeat early-morning fasting testing, and on looking for reversible contributors before anyone writes a prescription (Endocrine Society, 2026).

If you haven't done that groundwork yet, start there, not here. Both halves have their own guides: signs of low testosterone for the symptoms, the testosterone blood test for the measurement.

What it does well, and what it does not

The clearest read comes from the Testosterone Trials: 790 men aged 65 and over, all with levels under 275 ng/dL and symptoms, randomized to testosterone gel or placebo for a year (NEJM, 2016).

Read the middle two rows again, because they are the ones the advertising inverts. These men were genuinely deficient and were treated up to the mid-normal range of a young man, and testosterone still failed to move the primary vitality outcome. So if tiredness is your main complaint, take that as a cue to hunt for other causes before betting on TRT; our guide to persistent tiredness lists the ones to chase first.

What we now know about the heart

For a decade this was the open question, and it kept sensible men off treatment they needed.

TRAVERSE randomized 5,246 men aged 45 to 80 who had existing cardiovascular disease or high risk for it, all with symptoms and two fasting testosterone levels under 300 ng/dL, to testosterone gel or placebo, with a mean follow-up of 33 months. Heart attack, stroke or cardiovascular death occurred in 7.0% of the testosterone group and 7.3% of the placebo group, a hazard ratio of 0.96. Testosterone was noninferior to placebo (NEJM, 2023).

That is reassuring, and it is not a clean bill of health. The same trial found more atrial fibrillation, more acute kidney injury and more pulmonary embolism in the testosterone group. So the honest summary reads: in men like those enrolled, middle-aged and older with confirmed hypogonadism and raised cardiovascular risk, TRT did not raise the trial's primary composite risk of cardiovascular death, heart attack or stroke, and it was not risk-free either. Long-term safety, including prostate cancer risk, remains incompletely established on the Endocrine Society's own reading (Endocrine Society, 2026). And none of this evidence applies to men with normal levels taking it to feel younger.

The costs nobody puts in the advert

Fertility. Testosterone from outside switches off the signal that drives sperm production. The AUA is direct about it: the long-term impact on spermatogenesis must be discussed with any man interested in future fertility, and testosterone should not be prescribed to men currently trying to conceive. If children are a possibility, say so before the first prescription. Afterwards is too late to plan around it.

Thicker blood. Testosterone raises red cell production, so hemoglobin and hematocrit get measured before starting and monitored on treatment, because of the risk of polycythemia.

The prostate check. Under AUA guidance, PSA is measured in men over 40 before testosterone treatment; other guidelines individualize prostate assessment by age and risk.

It can become a long-term commitment. TRT suppresses your body's own testosterone and sperm production while you take it. Whether you can ever stop depends partly on why your level was low in the first place, and if you do stop, your own production may take time to come back. Starting is a bigger decision than "let's see how you feel for a month."

What careful treatment looks like

Before you start, expect at least two early-morning fasting testosterone tests, luteinizing hormone to establish where the problem sits, prolactin if LH is low or low-normal, hemoglobin and hematocrit, and prostate/PSA assessment appropriate to the guideline, your age and your risk. A careful prescriber also checks for reasons not to start, or to delay: fertility plans, a raised hematocrit, untreated severe sleep apnea, relevant prostate or breast cancer concerns, uncontrolled heart failure, a cardiac event in the past six months, thrombophilia.

Once you are on it, dosing aims at the middle of the normal range, not the top. Urology guidance puts the target in the middle tertile of the reference range, roughly 450 to 600 ng/dL for most laboratories. Higher is not the treatment goal, and it may buy you adverse effects instead of benefits.

Then come repeat tests of testosterone, hematocrit and PSA, on a schedule your doctor sets, together with an honest review of whether the symptoms that justified treatment have actually improved. If nothing has changed after several months at a proper level, revisit the diagnosis.

Six questions to ask before you start

1. What were my two morning testosterone results, and what was my LH? If the answer involves one afternoon test, stop.
2. What symptom are we treating, and how will we know it worked? Name it up front.
3. What is my baseline hematocrit, and what prostate assessment is appropriate for my age and risk? No baseline means no monitoring.
4. Do I want children in future? Have that conversation now. It cannot be retrofitted.
5. What happens if I stop? Ask what recovery might look like in your situation and whether the underlying cause is reversible. A clinic that glosses over this is selling, not treating.
6. Have we ruled out the reversible causes? Weight, sleep apnea, alcohol and medications all lower testosterone, and our guide to raising testosterone naturally puts numbers on each.

How to spot a bad clinic

• It treats a level that is not low, or one measured once, in the afternoon.
• It never mentions fertility, hematocrit or PSA.
• It talks about "optimizing" you into the top of the range, or above it.
• It bundles the prescription with supplements. Our review of testosterone boosters explains what those are worth.
• Nobody asks why your testosterone is low. Cleveland Clinic lists obesity, sleep apnea, opioids, alcohol and pituitary problems among the causes (Cleveland Clinic), several of which are treatable in their own right, no prescription required.

TRT changes lives for men who genuinely have testosterone deficiency. For everyone else it is an expensive, hard-to-reverse way to treat a problem they do not have. The blood test is what tells the two apart, and it costs a fraction of a year's prescriptions.

Frequently asked questions

Who is testosterone replacement therapy actually for?

Men who have both compatible symptoms and consistently low testosterone, confirmed on at least two early-morning fasting blood tests. The AUA treats total testosterone below 300 ng/dL as a reasonable diagnostic cut-off; the Endocrine Society avoids a single universal number and asks for unequivocally low results on an accurate, properly referenced assay. Treating a normal level is not TRT, it is a subscription.

What does TRT actually improve?

The best evidence comes from a year-long trial in men aged 65 and over with genuinely low levels. Testosterone reliably improved sexual activity, desire and erectile function, and mood improved a little. Energy and vitality did not budge, and the effect on walking distance was marginal. That is worth remembering, since energy is the thing most ads promise.

Is TRT bad for your heart?

The TRAVERSE trial put this to the test in over five thousand middle-aged and older men with confirmed hypogonadism and raised cardiovascular risk. Rates of cardiovascular death, heart attack or stroke were essentially the same on testosterone and placebo. The testosterone group did see more atrial fibrillation, acute kidney injury and pulmonary embolism, and safety beyond the trial's timeframe isn't fully established.

Does TRT make you infertile?

It suppresses sperm production while you take it. Urology guidance is blunt on this point. The long-term effect on sperm has to be discussed with any man who may want children, and testosterone should not be prescribed to men currently trying to conceive.

Do you have to stay on TRT for life?

Not always, but plan as if you might. External testosterone switches off your own production, so stopping means a recovery period while the hypothalamic-pituitary-gonadal axis restarts, and whether you can eventually stop depends partly on why your level was low to begin with. It is a commitment, not a casual experiment.

How do you tell a bad TRT clinic from a careful one?

Watch what they measure and what they skip. One afternoon test, a "low" level that isn't actually low, no mention of fertility, hematocrit or PSA, talk of "optimizing" you into the top of the range, supplements bundled with the prescription, and no curiosity about why your testosterone is low. Any of these tells you the business model before the doctor does.

References

1. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline · The Journal of Clinical Endocrinology & Metabolism, 2018
2. Statement on Testosterone Replacement Therapy · Endocrine Society, 2026
3. Evaluation and Management of Testosterone Deficiency: AUA Guideline · American Urological Association
4. Cardiovascular Safety of Testosterone-Replacement Therapy (TRAVERSE) · New England Journal of Medicine, 2023
5. Effects of Testosterone Treatment in Older Men (The Testosterone Trials) · New England Journal of Medicine, 2016
6. Low Testosterone (Male Hypogonadism) · Cleveland Clinic