TRT and Fertility: Why Testosterone Lowers Sperm Count

Testosterone therapy treats low testosterone, so it is easy to assume that more testosterone means more fertility. It is the opposite. Testosterone taken from outside the body lowers sperm production, sometimes to zero, and it has been studied as a male contraceptive. If you are on testosterone and want children, now or later, this page explains why and what to ask your doctor.

Why does testosterone lower sperm count?

Sperm production needs a very high level of testosterone inside the testes, about 20 to 100 times the level in the blood.¹ That local testosterone is made by the testes themselves, under hormone signals from the brain (LH and FSH). Testosterone therapy suppresses those signals, so the testes make less of their own testosterone and the level inside them falls.¹⁴ A deficiency of testosterone inside the testes can cut sperm production by 90% to 95%.¹

The effect is strong enough that the World Health Organization tested testosterone as a male contraceptive, publishing results on testosterone-induced azoospermia, meaning no sperm in the ejaculate, in 1990.³ In men misusing testosterone, a 2025 review reports azoospermia in more than 40%, and low counts or no sperm in about 66% to 77% of anabolic steroid users.¹

What do the guidelines say?

The AUA and ASRM joint guideline on male infertility advises against exogenous testosterone therapy for men who want current or future fertility.¹⁵ The AUA’s testosterone deficiency guideline also includes specific statements for men interested in preserving fertility.⁶ In short, testosterone treats symptoms of low testosterone; it is not a fertility treatment.

TRT and fertility: the evidence at a glance

How long does recovery take after stopping?

Usually months, not weeks. The best data come from an integrated analysis of 1,549 healthy men who took testosterone-based hormonal contraceptives and then stopped.² The median time for sperm to return to 20 million per mL was 3.4 months.² The probability of recovering to that level was:²

Recovery was faster in older men, in Asian men, with shorter treatment, with shorter-acting preparations and with higher sperm counts at baseline, although these factors changed the speed of recovery more than its extent.² Those were healthy volunteers on planned regimens. In men using higher doses for longer, recovery takes longer.¹ And recovery to your own previous level is not universal, particularly if semen quality was poor before treatment.⁴

Because sperm take about 74 days to develop, even after hormones recover it takes another two to three months for new sperm to reach the ejaculate.⁷

What about anabolic steroids?

Anabolic steroids used for training act the same way, often at higher doses. In the HAARLEM study of male amateur athletes, summarized in a 2025 review, testosterone and LH levels recovered earlier after stopping steroids, but testicular volume and sperm measures were still below baseline a year later.¹ If you have used steroids, tell your doctor; it changes how your fertility is evaluated.

What are the fertility-preserving options?

These are decisions for a urologist or reproductive endocrinologist, not something to try on your own. The main options they may discuss are:¹⁴

• hCG (human chorionic gonadotropin). It stimulates the testes to make their own testosterone.¹ It is the only FDA-approved therapy in its class, and studies show it can maintain sperm production even when testosterone therapy has suppressed the brain’s signals.⁴
• SERMs such as clomiphene or enclomiphene. They block estrogen’s brake on the brain’s hormone signals, raising LH and FSH. They are used off-label.¹⁴
• Aromatase inhibitors. They reduce the conversion of testosterone to estradiol. The 2024 AUA/ASRM guideline update endorses them in selected men with low testosterone and elevated estradiol; they are also off-label.⁴⁵
• Stopping testosterone with monitoring. Some men stop and let natural production return, with semen tests to track recovery.¹

Results vary. In one study of 94 infertile men who had misused anabolic steroids, only 15% achieved a pregnancy after at least three months of hCG and clomiphene.¹ That is a strong reason to plan before starting testosterone, not after.

What to do if you are on TRT and want a baby

1. Tell your prescriber that you are trying, or plan to try, to conceive.
2. Get a semen analysis to know your starting point. Our semen analysis results guide explains the numbers. Mail-in kits that send your sample to a lab are an option if a clinic visit is hard.
3. See a urologist with male fertility experience to plan stopping, switching or adding treatment.
4. Give it time. Plan for many months of recovery, and use our 90-day sperm health plan alongside medical treatment.
5. Get both partners evaluated if you have been trying for a year, or six months if your partner is 35 or older; see when to see a fertility specialist.

For lifestyle changes with evidence, see how to increase sperm count. More for partners in the Partners hub.