What Is TRT? Who It Suits, Who Should Avoid It, How to Start Safely

In the past few years TRT has become a trend, seen in gyms, videos and adverts. Some people talk about it like a magic pill that makes you young again; others fear it is a dangerous steroid. The truth lies in between. TRT is a medical treatment with real benefits for people who genuinely have the condition, and its risks are manageable when someone is monitoring you. I want you to understand this picture before you decide.

What is TRT?

TRT (testosterone replacement therapy) means giving testosterone from outside the body to replace what the body can't make enough of. The goal is to bring hormone levels back into the normal male range, not to push them above natural levels. That is different from steroid use for bodybuilding, which uses doses many times higher.

Forms used in Thailand include:

• Intramuscular injection of a medium-acting form, such as testosterone enanthate, every 1–3 weeks
• Intramuscular injection of the long-acting testosterone undecanoate, every 10–14 weeks
• A skin gel applied once a day

The choice depends on your lifestyle, chronic conditions and preferences. See the comparisons in Injections vs gel and Testosterone enanthate vs undecanoate.

Who is TRT suitable for?

The AUA, EAU and Endocrine Society guidelines agree that both of the following are needed:

1. Symptoms or signs of testosterone deficiency, especially sexual symptoms (see Symptoms of low testosterone)
2. Low morning fasting total testosterone on at least 2 tests

Before starting, the doctor should look for the cause and fix what can be fixed first, such as excess weight, sleep apnoea or certain medicines. A statement from the Endocrine Society in July 2026 emphasised that in overweight men with no other cause found, weight loss should be the first option, and that screening hormone levels in men without symptoms is not recommended.

Who shouldn't start, or needs assessment first

• Men planning to have children soon
• Men with prostate or breast cancer, or a prostate lump that hasn't been investigated
• A raised PSA that hasn't been assessed by a urologist
• Haematocrit (blood thickness) above 50% before starting
• Severe untreated sleep apnoea
• Severe difficulty urinating
• Uncontrolled heart failure, or a heart attack or stroke within the past 6 months
• A history of blood clots or a condition that makes blood clot easily

What are the benefits, and how big are they?

Large randomised trials such as the T Trials and TRAVERSE in men with genuinely low testosterone show that TRT helps as follows:

• Sexual desire and frequency of sexual activity improve most clearly; erections improve only slightly, and many men still need erection medicine as well (read ED)
• Mood and energy improve slightly in men with low mood, but it does not treat depression
• Anaemia with no other cause improves
• Muscle mass increases and fat decreases slightly, with clearer results when combined with exercise
• Bone density increases, but in TRAVERSE fractures were not reduced, and were in fact slightly more common than with placebo

What TRT has not been proven to do is slow ageing, extend life or prevent diabetes in the general population.

Heart safety: TRAVERSE and the label changes

TRAVERSE (Lincoff and colleagues, NEJM 2023) is the largest study on this question. It studied 5,246 men aged 45–80 with low testosterone and heart disease or high cardiovascular risk, comparing testosterone gel with placebo, with average follow-up of a little over 2 years.

Following these results, the US Food and Drug Administration (FDA) announced on 28 February 2025 that all testosterone products must add the TRAVERSE results to their labels, removed the boxed warning about cardiovascular risk, and required all products to carry a warning about raised blood pressure. Later, in June 2026, the FDA began a process to consider easing label wording about limits in older men and about the prostate; this is still a proposal, not a final decision.

In short, TRT is not as dangerous to the heart as was once feared, but it is not risk-free, so blood pressure, blood tests and ongoing monitoring are still needed. See the details in TRT side effects.

An important point that is often forgotten: fertility

Hormones from outside the body make the brain stop signalling the testicles, so sperm production falls or stops. TRT can't be used as contraception, but it can make it hard to have children. If you are still planning to have children, tell your doctor from the start, because there are other options that stimulate the testicles to work by themselves, as the doctor considers appropriate, and a semen analysis may be done before starting.

Starting TRT the right way

1. History, physical examination, and an assessment of mood, relationships and sleep.
2. Two morning blood tests with the basic panel (see Blood tests before starting TRT).
3. Discuss goals, options, risks and fertility before deciding together.
4. Choose the form and dose as assessed and prescribed by the doctor.
5. Follow-up in the first 3–6 months, checking hormone levels, haematocrit, PSA and blood pressure, then adjust the medicine.
6. Once stable, follow up at least once a year and assess whether symptoms have really improved. If they haven't improved within 3–6 months, the diagnosis should be reviewed.

When to see a doctor, and how the clinic can help

If you have symptoms that suggest low testosterone, or you are already using hormones without anyone monitoring you, now is a good time to get checked. While on TRT, if you have chest pain, breathlessness, swelling in one leg, unusual palpitations or sudden weakness in an arm or leg, go to hospital or call 1669 (Thailand's medical emergency number).

At Dr. Kris Clinic I look after you from assessing whether you genuinely meet the criteria, through blood tests and planning the form of treatment, to long-term follow-up, at the clinic in Surat Thani and online for parts of the follow-up. Consultations in English are available. Men aged 50 and over may also want to read Men's health after 50.