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urology

Low Sperm Count (Oligospermia): Causes & Treatment

Low sperm count (oligospermia) — fewer than 16 million sperm per milliliter, per WHO 2021 reference values — is one of the most common causes of male infertility. Causes include varicocele, hormone imbalances, prior infections, medications, and lifestyle factors. Many causes are treatable; a reproductive urologist or andrologist should guide evaluation and care.

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What counts as a low sperm count?

A semen analysis is the starting point for evaluating male fertility. It measures how many sperm are present, how well they move (motility), and whether their shape is normal (morphology). The World Health Organization's 6th edition manual (2021) defines the lower reference limit for sperm concentration at 16 million sperm per milliliter (the 5th percentile of fertile men) 3. Below this is called oligospermia. Severe oligospermia means fewer than 5 million per milliliter. When no sperm are found at all, the term is azoospermia.

A single abnormal semen analysis is not automatically diagnostic — results can vary from sample to sample based on recent illness, stress, or the time since the last ejaculation. Most specialists repeat the test before concluding there is a real problem 1.

What causes low sperm count?

Sperm production depends on the coordination of hormones, testicular function, and anatomy. Problems at any point along this chain can reduce sperm numbers 1.

Varicocele — enlarged veins in the scrotum that raise testicular temperature — is the most commonly identified correctable cause of male infertility. It is found in a substantial portion of men evaluated for fertility problems.

Hormonal causes include low levels of FSH, LH, or testosterone (hypogonadotropic hypogonadism), which can stem from pituitary or hypothalamic problems. External testosterone use — anabolic steroids or testosterone supplements — suppresses the body's own hormonal signal to the testes and can dramatically reduce sperm production, sometimes to zero.

Obstruction — a blockage in the epididymis, vas deferens, or ejaculatory ducts — can cause low or absent sperm in the ejaculate even when the testes produce sperm normally. Prior vasectomy, infection (including prior chlamydia or gonorrhea), or prior surgery can cause obstruction.

Genetic factors such as Klinefelter syndrome (an extra X chromosome) or Y-chromosome microdeletions affect a minority of men with severely low counts.

Medications including certain antibiotics, chemotherapy agents, and sulfasalazine can impair sperm production.

Lifestyle factors including heat exposure (hot tubs, tight clothing), smoking, heavy alcohol use, and anabolic steroid use are associated with lower sperm counts.

How is oligospermia evaluated?

A reproductive urologist will typically review your medical history, perform a physical exam (including checking for varicocele), and order blood tests to assess testosterone, FSH, LH, and prolactin levels 1. Genetic testing (karyotype, Y-chromosome deletion analysis) or testicular ultrasound may be recommended based on findings.

If a hormonal cause is found — such as low gonadotropins — medication can stimulate sperm production in some cases. This is different from testosterone replacement therapy, which actually suppresses sperm production and is avoided in men trying to conceive 2.

What treatments are available?

Treatment depends on the underlying cause 12:

  • Varicocele repair (varicocelectomy or embolization) can improve sperm counts and natural conception rates in men with palpable varicoceles and abnormal semen parameters. The AUA/ASRM guideline recommends considering varicocelectomy in men with palpable varicoceles, infertility, and abnormal semen parameters 2.
  • Hormone therapy with clomiphene citrate, hCG, or gonadotropins can stimulate sperm production when the cause is hormonal (hypogonadotropic hypogonadism).
  • Surgical sperm retrieval combined with in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) can achieve pregnancy even in men with very low counts or azoospermia, where a single sperm is injected directly into an egg 2.
  • Lifestyle changes — stopping anabolic steroids, reducing heat exposure, quitting smoking — may improve counts over several months, since the full sperm production cycle takes roughly 72–90 days.
  • When obstruction is the cause, surgical reconstruction or sperm retrieval combined with ART are the main options.

Natural supplements marketed for sperm health (antioxidants, coenzyme Q10, L-carnitine) are studied but evidence remains mixed and inconclusive; discuss any supplements with your urologist before starting them.

What specialist should you see — and how can Gale help?

Low sperm count is a urological condition evaluated and treated by a urologist, ideally one with subspecialty training in male infertility (a reproductive urologist or andrologist). Your partner may also be evaluated by a reproductive endocrinologist, as couple-level assessment shapes treatment decisions.

Gale does not directly provide urology subspecialty care, but a Gale clinician can review your health history, order initial lab work, discuss your options, and help you get to the right specialist prepared. If you have a confirmed low count and want to understand your next steps, a Gale visit is a reasonable starting point.

Common questions

Can low sperm count be treated without IVF?

Yes, depending on cause. Varicocele repair, hormone therapy, stopping anabolic steroids, and lifestyle changes can improve natural sperm counts. IVF with sperm injection is typically reserved for severe cases or when simpler treatments have not worked.

Does testosterone replacement therapy improve sperm count?

No — TRT suppresses the hormonal signals that drive sperm production and can reduce sperm count to very low levels. Men trying to conceive should not use TRT. Stopping it and using other hormone treatments may allow recovery, though timing varies.

How long does it take to improve sperm count with lifestyle changes?

The sperm production cycle takes about 72 to 90 days. Any changes — stopping smoking, reducing heat exposure, stopping steroid use — take at least two to three months before showing up in a semen analysis.

Is oligospermia always genetic?

No. Genetics accounts for a minority of cases, mainly severe oligospermia or azoospermia. More often, the cause is a varicocele, hormonal issue, prior infection, medication effect, or lifestyle factor.

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When to seek care promptly

  • —Pain or swelling in the testicles alongside fertility concerns — a scrotal exam is needed
  • —You have been trying to conceive for 12 months or more (or 6 months if your partner is over 35)
  • —History of cancer treatment, undescended testicles, or testicular surgery

This article provides general health education and does not replace evaluation by a urologist or reproductive specialist. Individual causes and treatments vary. Gale clinicians can support the initial workup but are not a substitute for subspecialty urological care.

References

  1. 1.Schlegel PN, Sigman M, Collura B, De Jonge CJ, Eisenberg ML, Lamb DJ, Mulhall JP, Niederberger C, Sandlow JI, Sokol RZ, Spandorfer SD, Tanrikut C, Treadwell JR, Oristaglio JT, Zini A (2021). Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline Part I. Journal of Urology. doi:10.1097/JU.0000000000001521 ✓Evaluation framework for male infertility including semen analysis interpretation, hormonal workup (FSH, LH, testosterone, prolactin), genetic testing, and physical examination for varicocele
  2. 2.Schlegel PN, Sigman M, Collura B, De Jonge CJ, Eisenberg ML, Lamb DJ, Mulhall JP, Niederberger C, Sandlow JI, Sokol RZ, Spandorfer SD, Tanrikut C, Treadwell JR, Oristaglio JT, Zini A (2021). Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline Part II. Journal of Urology. doi:10.1097/JU.0000000000001520 ✓Varicocelectomy recommendations for men with palpable varicocele and abnormal semen parameters; surgical sperm retrieval with IVF/ICSI; hormone therapy (clomiphene, hCG, gonadotropins); IUI and ART selection criteria
  3. 3.World Health Organization (2021). WHO Laboratory Manual for the Examination and Processing of Human Semen, 6th Edition. World Health Organization. link ✓Lower reference limit for sperm concentration: 16 million/mL (5th percentile from fertile men); total sperm count ≥39 million per ejaculate; normal morphology ≥4%; total motility ≥42%

3 sources, numbered by first appearance. General health information, not medical advice — synthetic demonstration content.