TRT stands for testosterone replacement therapy. It is a prescription treatment that gives testosterone to men whose bodies do not make enough of it because of a diagnosed medical condition.
Last reviewed: 12 October 2026
Testosterone replacement therapy treats androgen deficiency. That is a condition where the testes, or the hormone signals that control them, do not work as they should.
The word replacement matters. The aim is to bring a hormone the body is not making enough of back towards a normal level, not to top up a level that is already normal.
In Australia it is a prescription medicine. A doctor starts it and supervises it after a diagnosis.
Mixing these two up causes most of the confusion here. Testosterone is a hormone your body makes.
Testosterone therapy is a medicine.
As a hormone, Healthy Male says testosterone in adult men regulates bone health, red blood cell production, mood and behaviour, libido, fertility, and the prostate. It is also needed to make sperm.
That range is the point. A hormone doing that many jobs cannot be changed in isolation, which is why giving it as a medicine is a clinical decision.
The symptoms linked to low testosterone are real. They are also not specific to it.
Tiredness, low mood, poor sleep, low libido and loss of muscle have many causes. Most of those causes are more common than androgen deficiency.
One blood result does not settle it either. Testosterone rises and falls through the day and varies between days, so a single reading is only a snapshot.
We explain the test itself in our guide to the testosterone blood test.
Diagnosis requires repeated fasting morning testosterone measurements alongside symptoms and clinical assessment. LH, FSH and other markers may then help the doctor investigate the cause, with the exact tests depending on the person and the clinical guidance being followed.
The RACGP advises that samples be taken close to 8 am, that food can acutely reduce total testosterone, and that repeated measurements are needed to confirm a low result. It states that a diagnosis should never rest on a single testosterone level.
| What may be assessed | Why it matters |
|---|---|
| Symptoms and history | Symptoms are not specific, so they are read with everything else |
| Repeated morning samples | One reading can mislead, so a low result is confirmed on another day |
| LH, FSH and other markers | They may be added to help show where the cause sits, depending on the case |
| Other health conditions | Several common conditions lower testosterone on their own |
| Current medicines | Some medicines reduce testosterone, which changes what the result means |
| Fertility plans | Therapy suppresses sperm production, so this must be raised first |
History counts too. Healthy Male lists undescended testes, testicular surgery, fertility, infection and other illness among the things a clinician asks about.
If symptoms are what prompted the question, it is worth reading about low testosterone symptoms alongside any result.
The clinical aim is narrow. Where a man has diagnosed androgen deficiency, therapy aims to bring his testosterone back towards a level the body would normally hold.
That is an aim about biology, not a promise about how someone will feel. Results differ between people, and no article can tell you what yours would be.
Treatment may be considered where androgen deficiency has been confirmed through proper assessment. That is the situation the evidence and the clinical guidance address.
It is not a general treatment for non-specific symptoms, and it is not a response to an age related decline that has not been properly diagnosed. Where symptoms have another cause, the appropriate step is to find and address that cause.
Outcomes vary between individuals and no personal benefit can be promised. Anyone promising you a specific result is not describing medicine.
Using testosterone without a diagnosed deficiency, or above prescribed targets, or without medical supervision, is not the same as replacement therapy. It may carry different or greater risks.
Therapy carries recognised risks, and those risks are why it is supervised. Healthdirect lists side effects and complications of testosterone replacement therapy.
Those listed include acne or other skin reactions, male pattern hair loss, higher levels of red blood cells and prostate specific antigen, and reduced fertility in some people.
That is not an exhaustive list. It is a reasonable picture of the issues a doctor weighs and monitors.
Monitoring is routine rather than optional. Healthdirect notes that a doctor will regularly monitor testosterone levels with blood tests, and Healthy Male advises that screening for prostate disease in men using therapy should occur as it would for other men of the same age.
Healthy Male also frames effectiveness in terms of the person rather than the number, describing relief of the patient's leading symptom as the best clinical measure of effective management.
Some health conditions can make testosterone therapy unsuitable or require specialist assessment. Current Australian guidance highlights prostate or breast cancer, fertility plans and certain advanced prostate or heart conditions among the issues a doctor must consider.
Testosterone therapy suppresses sperm production and should not be started in men with current or imminent reproductive plans without specialist fertility advice.
Healthdirect makes the same point from the prescribing side. It notes a doctor will not prescribe testosterone therapy to a man who has prostate or breast cancer, or who is planning to try to have a child.
This is the consequence people most often miss. Anyone who may want children should raise it before anything starts.
A low reading is something to explain, not automatically something to replace. The RACGP notes that levels are commonly lowered in men with metabolic syndrome, type 2 diabetes, obesity, depression, obstructive sleep apnoea or chronic kidney disease.
It also names alcohol excess as a recognised cause, and notes that glucocorticoid and opioid medicines reduce testosterone. Where one of these is driving the result, treating that cause may be the better path.
Testosterone is a prescription only medicine here. It is started and supervised by a doctor after assessment.
Subsidy has its own rules. Healthy Male guidance states that PBS subsidised testosterone treatment must be provided by, or in consultation with, an eligible specialist such as an endocrinologist, urologist or registered sexual health physician, and the relevant clinical criteria must be met.
If you are weighing this up, these are fair questions for a doctor who knows your history.
Our guide to how long blood test results take explains what happens once samples are collected.
Testosterone replacement therapy. It is the medical use of testosterone to treat diagnosed androgen deficiency.
Yes, as a prescription medicine. It is started and supervised by a doctor after assessment.
Healthdirect lists acne or other skin reactions, male pattern hair loss, higher levels of red blood cells and prostate specific antigen, and reduced fertility in some people. That list is not exhaustive and monitoring is part of treatment.
Yes. It suppresses sperm production, and it should not be started in men with current or imminent reproductive plans without specialist fertility advice.
No. Diagnosis requires repeated fasting morning measurements read together with symptoms and clinical assessment.
No. Replacement treats a diagnosed deficiency. Using testosterone without a diagnosed deficiency is not medically equivalent to replacement therapy and may carry different or greater risks.
TRT is a legitimate treatment for a specific diagnosed condition. It is not a general remedy for feeling below par.
For most people the useful next step is not a decision about therapy. It is a proper assessment of what is actually going on.
This article is general information and is not medical advice. Decisions about testosterone therapy should be made with a qualified health professional who knows your history.