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Wellness · Men’s health

Testosterone in men, the honest biology of "andropause".

Testosterone falls with age, but true clinical deficiency is much less common than wellness clinics suggest. Here is when TRT is warranted, and the red flags.

Jump to how See red-flag signs
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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from evidence

    Every claim is checked against BSSM, Endocrine Society and NICE guidance — sources listed at the end.

  • 03

    No wellness hype

    Straight-talking and evidence-first — no pellet upsells, no lifetime subscriptions, no shortcuts.

Key facts

Testosterone in men at a glance.

The essentials, in plain English — normal decline, true deficiency, how it is diagnosed, and what starting TRT actually commits you to.

  • Normal decline

    Testosterone falls by roughly 1% per year after age 30 — that is normal, not a disease.

  • True deficiency is uncommon

    Male hypogonadism affects around 2–6% of adult men — far less than wellness clinics suggest.

  • Diagnosis is strict

    Requires at least two morning testosterone tests plus symptoms plus a workup for reversible causes.

  • A lifelong commitment

    Once you start TRT the testes shrink and stop producing testosterone — this rarely reverses cleanly.

  • Fertility falls fast

    Sperm production drops sharply on TRT — freeze sperm first if you may want children.

  • UK framework

    The British Society for Sexual Medicine (BSSM) standards give the accepted UK framework for testosterone deficiency.

Why this guide matters

More than a wellness pitch.

Most testosterone content online sells a treatment before establishing a diagnosis. These three points shape everything else on this page.

  • Age-related decline is not disease

    Testosterone falls with age in almost all men. That alone is not clinical hypogonadism, and does not need drugs.

  • True deficiency is uncommon

    Only 2–6% of adult men meet the criteria — biochemically low on two morning tests, with matching symptoms, and no reversible cause.

  • TRT is a lifelong decision

    Starting testosterone shuts down your own production and suppresses fertility. Go in eyes open, or not at all.

The evidence

The proper order to investigate low testosterone.

The BSSM- and Endocrine-Society-aligned pathway — reversible causes and repeat bloods first, treatment last.

  1. 01

    Bloods and causes

    Screen for reversible causes

    Obesity, obstructive sleep apnoea, alcohol, opioids and chronic illness all lower testosterone — fix those first.

  2. 02

    Bloods and causes

    Two morning fasting tests

    A single low result is not enough. Repeat testosterone on a second morning, fasting, before 11am.

  3. 03

    Bloods and causes

    Add SHBG, LH, FSH, prolactin

    The full panel separates primary (testicular) from secondary (pituitary) hypogonadism and flags a prolactinoma.

  4. 04

    Specialist

    MRI pituitary if secondary

    Low LH and FSH with low testosterone warrants imaging to rule out a pituitary tumour.

  5. 05

    Specialist

    BSSM-accredited review

    A BSSM-accredited andrologist confirms the diagnosis and rules out mimics before any prescription is written.

  6. 06

    Decision

    Optimise lifestyle first

    Weight loss, sleep, resistance training and alcohol reduction can restore testosterone without lifelong drugs.

  7. 07

    Decision

    Fertility preservation

    If you are young or may want children, freeze sperm before starting testosterone replacement.

Typical timeline: 3–6 months from first blood test to a considered treatment decision.

Signs it affects you

Signs, symptoms and overreach.

A quick self-check for the real biochemical and clinical picture — and one clear red flag that means you should not wait.

  • Low testosterone (biochemical)

    Repeatedly low morning testosterone on two separate fasting tests — the biochemical anchor.

  • Libido drop

    A persistent, unwanted fall in sexual desire — one of the most specific symptoms.

  • Persistent fatigue

    Tiredness that does not lift with rest, alongside low mood and reduced motivation.

  • Low mood

    Irritability, flatness and loss of drive — often mistaken for depression alone.

  • Muscle loss

    Reduced muscle mass and strength despite adequate protein and training.

  • Fracture risk

    Long-standing untreated deficiency lowers bone density and raises fracture risk.

  • Wellness-clinic overreach

    Being told a mid-range testosterone level is “suboptimal” and needs treatment — it usually does not.

  • Red flag: pituitary symptoms

    Headaches, visual field loss or galactorrhoea alongside low testosterone — urgent endocrinology.

How to do it

The right way to investigate and treat.

Eight steps, in rough order — start with a proper specialist workup, exhaust lifestyle, protect fertility, and monitor if TRT is truly indicated.

  • BSSM-accredited andrologist

    A specialist consultation is the right starting point — not a wellness clinic subscription.

  • Full androgen panel

    Morning fasting testosterone, SHBG, LH, FSH and prolactin — done twice, at least a week apart.

  • Lifestyle optimisation

    Sleep, weight, alcohol, resistance training — often enough to restore testosterone without drugs.

  • Weight loss for obesity-related low T

    Visceral fat converts testosterone to oestrogen. Losing 10% body weight often restores levels.

  • Testosterone gel (Testogel)

    Daily transdermal gel — steady levels, easy to stop if issues arise. First-line for most.

  • Testosterone injections

    Nebido (12-weekly) or Sustanon (3-weekly) — convenient but harder to fine-tune.

  • Fertility freeze before TRT

    Sperm banking before starting testosterone — non-negotiable if children are on the horizon.

  • Monitor haematocrit and PSA

    Regular bloods for erythrocytosis and prostate markers are mandatory on treatment.

What this guide is based on

The sources behind every claim on this page.

UK specialist society and international endocrine standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

If you have symptoms of low testosterone, please see your GP or a BSSM-accredited andrologist — a proper diagnosis is not the same as an online questionnaire.

  • British Society for Sexual Medicine (BSSM). Guidelines on adult testosterone deficiency.

  • Endocrine Society. Clinical practice guideline on testosterone therapy in men with hypogonadism.

  • NICE Clinical Knowledge Summary. Testosterone deficiency.

  • British Association of Urological Surgeons (BAUS). Men’s health resources.

Red flags

When TRT is the wrong answer.

Situations where testosterone therapy is contraindicated, complicated, or being sold irresponsibly — do not ignore any of them.

  • Prostate cancer history

    Active or recent prostate cancer is a strong contraindication to testosterone replacement.

  • High or rising PSA

    Warrants urological assessment before any consideration of testosterone therapy.

  • Rapidly progressive symptoms

    Sudden, severe symptoms suggest a pituitary or testicular problem — see a specialist urgently.

  • Untreated sleep apnoea

    TRT can worsen sleep apnoea. Diagnose and treat it first — do not start testosterone on top.

  • Erythrocytosis on TRT

    Rising haematocrit above 54% raises stroke and clot risk — dose reduction or venesection needed.

  • Fertility not addressed

    Starting TRT without banking sperm, when children are wanted, is a serious oversight.

  • Wellness clinic pushing pellets

    Subcutaneous testosterone pellets are unlicensed in the UK and hard to remove — walk away.

  • Concurrent anabolic steroid use

    AAS use complicates diagnosis and management — be honest with the clinician about it.

  • Pituitary tumour features

    Headaches, visual changes or galactorrhoea need urgent imaging and endocrinology input.

Making it stick

Treat it as a lifelong decision.

Four principles to keep in mind — the ones that separate a considered specialist decision from a wellness-clinic subscription.

A quiet reminder

A number on a screen is not a diagnosis.

A single testosterone reading, however framed, does not by itself justify lifelong hormone therapy. Ask for the full workup before you sign anything.

  1. 01 Baseline

    Age-related decline is normal

    A ~1% annual fall from age 30 is biology, not disease. Not everyone with a low-normal number needs treatment.

  2. 02 Diagnosis

    Get the diagnosis right

    Two morning fasting tests plus symptoms plus a proper workup — that is the standard, not a single afternoon reading.

  3. 03 Fertility

    Decide about fertility first

    TRT suppresses sperm production, often permanently. If you want children, freeze sperm before you start.

  4. 04 Commitment

    Treat it as a lifelong contract

    Once you start, stopping usually leaves you worse than before. Go in with a specialist, monitored properly.

Frequently asked

Everything we get asked about testosterone in men.

Quick answers on diagnosis, TRT, fertility, pellets and where to start if you have symptoms.

  • Is “low T” really a widespread problem?

    True hypogonadism affects around 2–6% of adult men. Wellness clinics blur the line between age-related decline and disease — most men with a mid-range level do not need treatment.

  • How is it properly diagnosed?

    At least two morning fasting testosterone tests, plus specific symptoms (low libido, fatigue, muscle loss), plus a workup for reversible causes such as obesity, sleep apnoea and opioids.

  • Will TRT make me infertile?

    Exogenous testosterone suppresses the brain’s signals to the testes, and sperm production drops sharply — often to zero. If you may want children, bank sperm before starting.

  • Can I stop TRT if I change my mind?

    Yes, but your own production may not recover cleanly. Many men feel worse after stopping than they did before starting. It is best considered lifelong.

  • Are testosterone pellets a good idea?

    Pellets are unlicensed in the UK, cannot be dose-adjusted once implanted, and are hard to remove if problems arise. Most UK andrologists use gel or licensed injections instead.

  • What should I do first if I feel low energy and low libido?

    See your GP for morning testosterone, thyroid, iron and mood assessment. Address sleep, weight and alcohol before considering TRT — many men improve without it.

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