TRT in Your 20s and 30s: Why Young Men Are Starting, and What It Costs

He is 27. He found the clinic through a podcast advert: a finger-prick test posted to his flat, a video call with a doctor, and a vial of testosterone delivered a week later. His result had been 13 nmol/L, which is in the normal range, but the clinic described it as "suboptimal for your age".

Within two months he felt great. More energy, better workouts, a stronger sex drive. Eighteen months later, he and his partner started trying for a baby. Nothing happened. A semen test showed a sperm count of zero.

This is not a rare story, and it is becoming more common. Testosterone therapy, once mainly prescribed to older men with clear deficiency, is now being marketed directly to men in their twenties and thirties. Some of them genuinely need it. Many do not, and few are told the full cost before they start.

How common is it becoming?

The rise is easiest to see in the United States. A study of US state prescription records by Selinger and Thallapureddy found that between 2018 and 2022 the number of people prescribed testosterone rose by 86% among 25 to 34 year olds, compared with 12% in people over 65. These figures include women and people receiving gender-affirming care, so they do not show the rise in young men alone, but they point in the same direction as what clinics report.

In England, community prescribing of testosterone products rose by about 52% between 2020/21 and 2024/25, according to NHS prescription data reported in the Pharmaceutical Journal. Specialists quoted there say much of the NHS rise is in older men with other health problems, but they also warn that some private clinics apply looser thresholds and higher doses than the NHS would.

That gap is where most young men come in. Private online clinics are easy to find, quick, and often willing to treat results that a GP or endocrinologist would call normal.

Why young men are interested

The appeal is easy to understand. Social media is full of men in their twenties showing physiques, energy and confidence they credit to testosterone. Clinics advertise during sports podcasts. And many young men genuinely do feel tired, unmotivated and flat, for reasons that are real.

The question is whether testosterone is the cause, and whether it is the right fix.

What counts as low?

UK guidance from the British Society for Sexual Medicine is clear about how deficiency should be diagnosed:

• a blood test taken in the morning, between 7 and 11am, ideally fasted;
• a repeat test, because a single result can be misleading;
• total testosterone below 12 nmol/L suggests possible deficiency, and below 8 nmol/L usually needs treatment, together with symptoms.

A one-off finger-prick test taken at any time of day is not a diagnosis. Testosterone varies through the day and from day to day, and it falls after a poor night's sleep, a heavy session in the gym or a short illness. See what blood test checks your testosterone.

There is no separate "optimal" range for young men that justifies treating a normal result. Testosterone does fall with age, but a 27-year-old at 13 nmol/L is not deficient.

The real causes of low testosterone in young men

When a young man's testosterone is genuinely low, there is almost always a reason, and finding it matters more than replacing the hormone. The common ones include:

• Excess body fat, especially around the waist. This is the most common cause, and weight loss often raises testosterone substantially. See stubborn belly fat in men.
• Poor or short sleep, and sleep apnoea, which is under-diagnosed in younger men.
• Past anabolic steroid use, which can suppress natural production for months or years. See testosterone recovery after steroids.
• Opioid painkillers and some other medicines.
• Heavy drinking and regular cannabis use, though the evidence for cannabis is mixed.
• Conditions that are easy to miss, such as a raised prolactin, Klinefelter syndrome, a varicocele or iron overload.

Some of these are serious. A pituitary tumour causing high prolactin, for example, needs treating in its own right, and starting testosterone can hide it. This is why a proper work-up includes LH, FSH and prolactin, not just testosterone. See what causes low testosterone.

The cost nobody mentions: fertility

This is the most important thing for any young man considering testosterone.

When you take testosterone, your brain senses that levels are high and switches off the two hormones, LH and FSH, that tell your testes to make testosterone and sperm. Blood testosterone goes up, but testosterone inside the testes falls, and sperm production slows or stops.

This effect is so reliable that testosterone has been studied as a male contraceptive. In a World Health Organization trial published in 1990, about two in three healthy men given weekly testosterone injections had no sperm at all within six months. See will TRT make you infertile?

The good news is that this usually reverses after stopping. An analysis by Peter Liu and colleagues of 30 studies and more than 1,500 men in hormonal contraception trials estimated that about two-thirds had sperm counts back to normal within six months of stopping, and almost all within two years.

But those were young, fertile men treated for a defined period in a trial. Men who have used testosterone for years, at higher doses, or who were older or had low counts to begin with, may take longer to recover, and some may need treatment to restart production. If you might want children, this needs discussing before you start, not when you are already trying.

Other things to know before starting

• It is usually long-term. Your own production is switched off while you take testosterone. Stopping often leads to a period of very low levels while your body restarts, which can feel worse than before you began.
• It thickens the blood. Testosterone raises haematocrit, the proportion of red blood cells. This needs regular monitoring, because very high levels increase the risk of clots.
• It can cause acne, breast tenderness and testicular shrinkage. See TRT side effects.
• It needs proper follow-up. UK guidance recommends checks at 3, 6 and 12 months, then yearly.
• The heart evidence is reassuring in older men, but there is little long-term data in men who start in their twenties. See is TRT safe for your heart?

When TRT is the right answer for a young man

None of this means young men should never take testosterone. For men with confirmed deficiency caused by a condition such as Klinefelter syndrome, damage to the testes, or a pituitary problem, testosterone therapy can be life-changing, and delaying it does them no favours.

The test is simple: consistent symptoms, repeated morning results that are clearly low, a search for the cause, and an honest conversation about fertility. If a clinic is willing to start treatment without those, that tells you something about the clinic. See how to tell a good online TRT clinic from a bad one.

If fertility matters to you

For men with low testosterone who want to keep their fertility, specialists sometimes use medicines that work by raising the body's own LH and FSH, such as hCG or clomiphene, rather than testosterone itself. Clomiphene is used off-label in men in the UK, and hCG is licensed only for specific conditions, so both need specialist supervision, but they are worth asking about. See enclomiphene and Clomid explained.

What to try first

If your testosterone is at the low end of normal and you feel flat, these have the best evidence for making a difference:

• Lose excess weight, especially from the waist.
• Protect seven to nine hours of sleep, and get checked for sleep apnoea if you snore.
• Lift weights two to four times a week.
• Cut back on alcohol.
• Treat low mood directly; it often looks like low testosterone. See low testosterone and depression.

Give it three to six months, then retest in the morning. Many men find their numbers and their energy improve without a prescription. See how to increase testosterone naturally.

The bottom line

Testosterone therapy works, and for young men with genuine deficiency it can be the right treatment. But it is being sold to men in their twenties and thirties whose levels are normal, often after a single test, and usually without a clear explanation that it switches off sperm production. Get a proper diagnosis, look for the cause, and if you might want children, put that conversation first.

Common questions

Is it safe to start TRT in your 20s?

It can be, if you have confirmed deficiency and are properly monitored. But it usually means long-term treatment, it suppresses sperm production, and there is little long-term data in men who start young. It should not be used to treat a normal result.

Will TRT make me infertile?

It suppresses sperm production in most men, often to zero within months. This usually reverses after stopping, but recovery can take a year or more, and is slower after long or high-dose use.

What testosterone level is low for a young man?

UK guidance treats total testosterone below 12 nmol/L as possible deficiency and below 8 nmol/L as usually needing treatment, based on repeated morning tests together with symptoms. There is no separate higher threshold for young men.

Why is my testosterone low at 25?

The most common reasons are excess body fat, poor sleep, past steroid use, opioids and heavy drinking. Less common but important causes include raised prolactin, Klinefelter syndrome and iron overload, so a proper work-up matters.

Can I come off TRT once I start?

Yes, but your own production has been switched off, so there is usually a period of low testosterone while it restarts. This should be planned with a doctor rather than done abruptly.

Sources: Selinger CP, Thallapureddy K, Cross-sectional analysis of national testosterone prescribing through prescription drug monitoring programs, 2018-2022, 2024 (PMID 39196907) · Pharmaceutical Journal, Moving the goalposts: the worrying rise of testosterone replacement therapy, citing NHS Business Services Authority Prescription Cost Analysis, England · British Society for Sexual Medicine, Guidelines on male adult testosterone deficiency · World Health Organization Task Force on Methods for the Regulation of Male Fertility, Contraceptive efficacy of testosterone-induced azoospermia in normal men, Lancet 1990;336(8721):955-9 · Liu PY et al., Rate, extent, and modifiers of spermatogenic recovery after hormonal male contraception, Lancet 2006;367(9520):1412-20 · Bhasin S et al., Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline, J Clin Endocrinol Metab 2018;103(5):1715-44 · Educational only, not medical advice.

Keep reading: Will TRT make you infertile? · Online TRT clinics · What causes low testosterone? · TRT or natural testosterone? · TRT side effects · Blood test: what to check