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Health condition · Clinically reviewed

Low sperm count, explained - from varicocele to assisted reproduction.

A low count usually has no symptoms of its own - it is often found only when a couple is investigated for infertility. Most causes are identifiable, and many are treatable.

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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 guidance

    Checked against NICE CG156, BAUS and peer-reviewed andrology sources you can see at the end.

  • 03

    Current for 2026

    Reflects WHO 2021 reference values, modern assisted-reproduction pathways and fertility-preservation options.

Key facts

Low sperm count at a glance.

The essentials, in plain English - what it is, why it happens, and how it’s assessed in the UK today.

  • What it is

    A sperm concentration below WHO reference values (under 16 million/mL, WHO 2021 6th edition) - a spectrum from mild reduction to a complete absence of sperm.

  • The spectrum

    Oligozoospermia (low count) through to azoospermia (no sperm on analysis) - see our separate guide on male infertility for the wider picture.

  • Most correctable cause

    Varicocele - enlarged scrotal veins - is the single most common treatable contributor found on examination.

  • Usually silent

    Most men with a low count have no other symptoms - it is often picked up only when a couple struggles to conceive.

  • Two samples, not one

    NICE recommends two semen analyses four to twelve weeks apart before drawing conclusions - counts vary naturally between samples.

  • Lifestyle first

    Stopping smoking, moderating alcohol, losing excess weight and avoiding heat exposure are first-line and cost nothing.

Why this guide matters

A structured work-up, not guesswork.

A low count can come from many different places in the reproductive pathway. The three points below shape everything else on this page.

  • Causes fall into three groups

    Pre-testicular (hormonal), testicular (varicocele, genetic, damage) and post-testicular (obstruction) - each needs a different investigation and treatment path.

  • Lifestyle is genuinely first-line

    Smoking, alcohol, obesity, heat exposure and anabolic steroids all measurably affect sperm parameters - and are the first thing addressed, always.

  • A low count is not the end of the story

    From varicocele repair to ICSI and surgical sperm retrieval, there is a well-established ladder of options for most causes.

How the diagnosis is made

From first semen analysis to a clear plan.

The steps a UK GP or andrology specialist will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    History and examination

    Fertility history, past mumps, undescended testes, torsion, chemotherapy or radiotherapy, medication and heat exposure, plus testicular volume and varicocele on examination.

  2. 02

    Assessing

    First semen analysis

    A WHO-standard semen analysis after two to seven days of abstinence, assessing concentration, motility and morphology.

  3. 03

    Assessing

    Second sample, four to twelve weeks later

    A confirmatory sample - spermatogenesis takes around three months, so results can genuinely change between tests.

  4. 04

    Confirming

    Hormone profile

    FSH, LH and testosterone distinguish a testicular problem from a hormonal one driving the low count - see our guide on hypogonadism.

  5. 05

    Confirming

    Scrotal ultrasound

    Confirms or excludes varicocele and looks for structural testicular abnormalities in a specialist andrology clinic.

  6. 06

    Preparing

    Genetic testing if severe

    Karyotype, Y-chromosome microdeletion and CFTR (cystic fibrosis) testing when the count is very low or absent, arranged through specialist commissioned genetics.

  7. 07

    Preparing

    Specialist andrology MDT

    Andrology, urology and fertility specialists jointly plan next steps, including whether assisted reproduction is the right route.

Typical timeline: two semen analyses over three months, then a settled plan.

Symptoms

What low sperm count actually looks like.

Usually nothing at all - and that’s the point. The features below, and the moments that mean it’s time to escalate.

  • Difficulty conceiving

    The most common presentation - male infertility contributes to around half of couples who struggle to conceive after a year of trying.

  • No symptoms at all

    Most men feel entirely well - a low count is a laboratory finding, not something you would notice day to day.

  • Reduced libido or energy

    Points towards a hormonal cause such as hypogonadism rather than a purely testicular one.

  • A visible or palpable varicocele

    A soft, dragging scrotal swelling - classically described as feeling like a bag of worms - found on standing examination.

  • Relevant history

    Undescended testes in childhood, testicular torsion, mumps orchitis, chemotherapy or previous vasectomy all narrow down the likely cause.

  • Heat exposure

    Frequent hot tub use, prolonged laptop use on the lap, or occupations with high scrotal heat exposure can lower counts reversibly.

  • Anabolic steroid or medication use

    Anabolic steroids, some antihypertensives and certain other drugs can suppress sperm production directly.

  • Red flag - absent vas deferens

    A vas deferens that cannot be felt on examination raises the possibility of CBAVD and warrants CFTR testing.

Treatment

How low sperm count is treated in the UK.

Lifestyle change first, treat any underlying hormonal or structural cause next - and assisted reproduction where it’s still needed.

  • Lifestyle modification

    Stopping smoking, reducing alcohol, losing weight and avoiding heat exposure and anabolic steroids - first-line for everyone, regardless of cause.

  • Gonadotrophin therapy

    For hypogonadotropic hypogonadism - hCG and FSH-based treatment stimulates sperm production directly, unlike testosterone replacement.

  • Varicocele repair

    Varicocelectomy is offered selectively - evidence on pregnancy rates is mixed, but many specialists still recommend it for a clinically significant varicocele.

  • Antioxidant supplementation

    Selective evidence for certain antioxidant combinations - discussed with your specialist rather than used as a stand-alone fix.

  • IUI, IVF or ICSI

    Assisted reproduction for significant oligozoospermia - ICSI in particular can achieve fertilisation with very low counts, arranged via specialist commissioned fertility services.

  • Surgical sperm retrieval (TESE/micro-TESE)

    For azoospermia - specialist commissioned surgical retrieval of sperm directly from testicular tissue for use with ICSI.

  • Fertility preservation

    Sperm banking before chemotherapy or radiotherapy - arranged urgently, ideally before treatment starts, through specialist commissioned services.

  • Genetic counselling

    Where a hereditary cause such as Klinefelter syndrome or a Y-chromosome microdeletion is found, counselling explains implications for the man and any children.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society 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.

Your GP or fertility specialist knows your history and can tell you which parts apply to you. If in doubt, get seen.

  • NICE. Fertility problems: assessment and treatment (CG156).

  • British Association of Urological Surgeons (BAUS). Male infertility and varicocele guidance.

  • World Health Organization. WHO laboratory manual for the examination and processing of human semen, 6th edition (2021).

  • European Association of Urology (EAU). Guidelines on sexual and reproductive health - male infertility.

Red flags

When it needs urgent attention.

Most low counts are manageable in a routine fertility pathway. These are the situations that aren’t - and where a specialist opinion is needed sooner.

  • Testicular lump or hardness

    Any new lump, hardness or change in the testicle needs urgent examination to exclude testicular cancer, regardless of fertility concerns.

  • Sudden severe testicular pain

    Could indicate testicular torsion - a surgical emergency needing assessment within hours, not days.

  • Absent vas deferens on examination

    Raises suspicion of CBAVD, often linked to being a cystic fibrosis carrier - warrants CFTR gene testing before assisted reproduction.

  • Very low or zero count (azoospermia)

    Needs prompt specialist andrology referral to distinguish an obstructive from a non-obstructive cause before options narrow.

  • Signs of Klinefelter syndrome

    Small firm testes, tall stature or gynaecomastia alongside infertility should prompt karyotype testing.

  • Before chemotherapy or radiotherapy

    Sperm banking is time-critical - ask for an urgent fertility-preservation referral before treatment starts, not after.

  • Features of hypogonadism

    Low libido, fatigue, reduced body hair or erectile dysfunction alongside a low count point to a hormonal cause needing its own work-up.

  • History of vasectomy wanting reversal

    A previous vasectomy causing current infertility needs a distinct conversation about reversal versus surgical sperm retrieval.

  • Recurrent orchitis or genital infection

    Ongoing infection can obstruct or damage sperm production and needs treating before fertility assessment continues.

Living with it

An investigable condition, with a clear pathway.

Four things that make the biggest difference while you’re being investigated - patience with timing, small lifestyle changes, keeping cool, and leaning on support.

A quiet reminder

A number on a form is not the whole story.

Sperm count is one part of a much bigger fertility picture - context and trend matter more than a single result.

  1. 01 Timing

    Two tests, not one

    A single semen analysis is a snapshot - counts naturally vary, so don’t judge your fertility from one result alone.

  2. 02 Habits

    Small changes add up

    Stopping smoking, cutting back on alcohol and losing excess weight can measurably improve sperm parameters over about three months.

  3. 03 Heat

    Keep things cool

    Avoid frequent hot tubs, saunas and prolonged laptop use directly on the lap - testicular temperature matters for sperm production.

  4. 04 Together

    It’s a shared journey

    Male-factor infertility affects both partners emotionally - many couples find support through Fertility Network UK alongside clinical care.

Frequently asked

Everything we get asked about low sperm count.

Quick answers on causes, testing, treatment and fertility options.

  • What counts as a low sperm count?

    A sperm concentration below the WHO 2021 reference value of 16 million per millilitre. It is a spectrum - mild oligozoospermia through to azoospermia, where no sperm are found at all - so the degree matters as much as the label.

  • Does a low count mean I can’t have children?

    No. Many men with a low count still conceive naturally, and assisted reproduction techniques such as IUI, IVF and ICSI can help even with very low counts. A low count lowers the odds per cycle rather than ruling out fatherhood.

  • What is the most common treatable cause?

    Varicocele - enlarged veins in the scrotum - is the most frequently identified correctable cause. Not everyone with a varicocele needs surgery, and the evidence on whether repair improves pregnancy rates is mixed, so this is discussed case by case.

  • Can lifestyle changes really make a difference?

    Yes, to a meaningful degree. Stopping smoking, moderating alcohol, losing excess weight and avoiding heat exposure and anabolic steroids can improve sperm parameters over roughly three months, which is how long a full cycle of sperm production takes.

  • Should I take testosterone to improve my fertility?

    No - this is a common misconception. Testosterone replacement actually suppresses natural sperm production. If a hormonal cause is found, gonadotrophin therapy is used instead, because it stimulates rather than switches off the testes.

  • When would I need genetic testing?

    Usually when the count is very low or completely absent. Karyotype testing, Y-chromosome microdeletion analysis and CFTR gene testing help identify Klinefelter syndrome, genetic deletions or a cystic fibrosis carrier status, all of which affect treatment choice and future family planning.

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