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Men's health

Low Sperm Count: What Causes It and What Can Be Done

Low sperm count (oligospermia) is a common contributor to male infertility, but it is often treatable. Many causes are reversible, including varicocele, hormonal imbalances, and lifestyle factors. The recommended starting point is a semen analysis and clinical evaluation, which identify the underlying cause and guide treatment that actually helps.

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What does the semen analysis actually measure?

A semen analysis is the foundational test for evaluating male fertility 1. It reports several numbers that together tell a more complete story than count alone:

  • Concentration — sperm per milliliter of semen
  • Total count — total number of sperm in the full ejaculate
  • Motility — the percentage moving well (forward progression matters, not just any movement)
  • Morphology — the percentage with normal shape
  • Volume — total amount of semen

All of these affect fertility. A man with a moderate count but excellent motility may conceive without difficulty; another with a count in the normal range but very poor morphology may face challenges. Clinicians typically want at least two analyses done several weeks apart before drawing firm conclusions, because sperm count varies naturally from sample to sample 1.

What are the common causes of low sperm count?

There are many reasons sperm production can be reduced. Some are structural, some hormonal, some driven by medications or lifestyle 1.

Varicocele is an enlargement of the veins draining the testicle — similar to varicose veins in the leg. It is the most commonly identified and surgically correctable cause of male infertility 1. By raising the temperature around the testicle, it impairs sperm production.

Hormonal imbalances — sperm production depends on a hormonal chain involving the pituitary gland and testosterone. Low testosterone, elevated prolactin, or thyroid problems can all suppress production. These are identified through blood testing 2.

Infections — some sexually transmitted infections (particularly chlamydia and gonorrhea, if untreated) can scar the reproductive tract. Mumps orchitis can impair sperm production directly 3.

Genetic causes — conditions like Klinefelter syndrome (an extra X chromosome) or Y chromosome microdeletions impair sperm production at a fundamental level. Genetic testing identifies these, and the results affect treatment options 1.

Undescended testicle (cryptorchidism) — testicles that do not descend normally before birth tend to produce fewer sperm, even if surgically corrected in childhood 1.

Anabolic steroids and testosterone replacement — using exogenous testosterone or anabolic steroids (including for bodybuilding) directly suppresses the body's own sperm production, often dramatically 2. This effect may reverse after stopping, but recovery can take many months.

Certain medications — some antibiotics, calcium channel blockers, chemotherapy drugs, and others can impair sperm production or function. A complete medication list is essential for any fertility evaluation.

Heat exposure — the testicles need to be slightly cooler than core body temperature to produce sperm optimally. Frequent hot tub, sauna, or laptop-on-lap exposure can modestly reduce production. This effect is generally temporary.

Obesity — excess body fat alters hormone levels in ways that can suppress sperm production.

Smoking, alcohol, and recreational drugs — all are associated with reduced sperm count and quality.

What can actually be done — matched to the cause

The treatments that work depend on why sperm count is low. Evaluation comes before advice 1.

For varicocele: surgical repair (varicocelectomy) can improve sperm parameters in many men; it is one of the better-supported interventions in male infertility 1.

For hormonal causes: replacing deficient hormones or addressing the underlying problem (thyroid, pituitary) can restore sperm production in some cases 2.

For anabolic steroid or testosterone use: stopping is the necessary first step. A fertility specialist may use medications to help restart natural production.

For lifestyle factors: stopping smoking, moderating alcohol, avoiding recreational drugs, maintaining a healthy weight, and reducing heat exposure are reasonable, low-risk steps to take while pursuing evaluation.

For genetic causes: some can be worked around with assisted reproductive techniques such as intracytoplasmic sperm injection (ICSI) even when counts are very low; others require donor sperm 1.

When no cause is found (idiopathic): some clinicians trial empirical treatments. Your specialist will discuss realistic expectations honestly.

When is it time to involve a specialist?

A primary-care clinician can order a semen analysis and initial blood work. If infertility is the concern, a urologist specializing in male reproductive medicine — sometimes called a reproductive urologist or andrologist — has the most targeted expertise 1.

If you and a partner have been trying to conceive for 12 months without success (or 6 months if the female partner is over 35), the standard recommendation is to evaluate both partners 1. Infertility is a couple's issue roughly half the time, and a combined workup is more efficient.

A reproductive endocrinologist may also be involved depending on the couple's situation and treatment plan.

Common questions

Can a low sperm count improve on its own?

It depends on the cause. If a reversible factor is involved — such as anabolic steroid use, a hormonal problem, or lifestyle factors — removing or treating that cause can lead to meaningful improvement. A structural cause like varicocele may improve with surgical repair. Genetic causes do not reverse, but assisted reproduction may still be possible. The answer to this question requires knowing what is causing the low count.

Does testosterone replacement improve sperm count?

No — the opposite. Exogenous testosterone, including prescribed TRT, suppresses the body's own sperm production by shutting down the hormonal signals that drive it. Men who want to preserve or restore fertility while managing low testosterone need a specialist conversation before starting TRT, because recovery after stopping can take many months.

How many semen analyses are needed for a reliable result?

At least two, done several weeks apart. Sperm count varies naturally from sample to sample — illness, stress, and abstinence interval all affect a single result. Two tests give a more reliable picture of a man's actual sperm production.

Should my partner be evaluated at the same time?

Yes, ideally. Male and female factors contribute roughly equally to infertility. Evaluating both partners together is more efficient and avoids spending time optimizing one side while an unaddressed issue on the other side limits success.

Can hot tubs really affect sperm count?

Frequent or prolonged heat exposure to the scrotum — from hot tubs, saunas, or laptops resting on the lap — can modestly suppress sperm production because testicles function best slightly below core body temperature. The effect is generally temporary and reverses when the exposure stops. It is rarely the sole cause of a severely low count, but reducing it is a simple, low-risk step.

Talk to a clinician

Nina Osei, NP — Nurse Practitioner

checkups, refills & skin. Gale can match you with a licensed clinician for a visit.

Find care →

When to seek care

  • —A lump or swelling in a testicle alongside fertility concerns — evaluate the lump first
  • —Current or recent use of testosterone replacement, anabolic steroids, or SARMs — disclose this immediately; stopping may be the first required step
  • —History of cancer treatment (chemotherapy or pelvic radiation) — requires a specialized fertility conversation before any further intervention

This article provides general health information and is not a diagnosis or personalized treatment plan. Work with a licensed clinician to evaluate your fertility concerns — the right treatment depends on the underlying cause.

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 ✓Semen analysis parameters, causes of male infertility including varicocele and genetic conditions, treatment approach and specialist referral thresholds
  2. 2.Mulhall JP, Trost LW, Brannigan RE, Kurtz EG, Redmon JB, Chiles KA, Lightner DJ, Miner MM, Murad MH, Nelson CJ, Platz EA, Ramanathan LV, Lewis RW (2018). Evaluation and Management of Testosterone Deficiency: AUA Guideline. Journal of Urology. doi:10.1016/j.juro.2018.03.115 ✓Hormonal causes of low sperm count, testosterone replacement suppressing endogenous sperm production, hormonal evaluation for infertility
  3. 3.Workowski KA, Bachmann LH, Chan PA, Johnston CM, Muzny CA, Park I, Reno H, Zenilman JM, Bolan GA (2021). Sexually Transmitted Infections Treatment Guidelines, 2021. MMWR Recommendations and Reports. doi:10.15585/mmwr.rr7004a1 ✓Untreated chlamydia and gonorrhea as causes of reproductive tract scarring that can impair male fertility

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