Testosterone and Male Fertility: How TRT Affects Sperm Production

Testosterone replacement therapy (TRT) often lowers sperm production, sometimes to zero, even while your blood testosterone looks normal or high. More testosterone in the blood does not mean more sperm. Guidelines say men who are trying to conceive should not be prescribed testosterone, and men who want children later should discuss fertility before they start (AUA 2018).

Why does testosterone therapy lower sperm count?

Sperm production depends on two signals from the pituitary gland: luteinizing hormone (LH), which tells the testicles to make their own testosterone, and follicle-stimulating hormone (FSH), which drives sperm production directly. When testosterone comes from outside the body, the brain reads it as "enough" and turns both signals down.

The testosterone that sperm need is the testosterone made inside the testicles (intratesticular testosterone), and it sits at far higher levels than what a blood test measures. In a randomized trial of 29 healthy men, blood testosterone was about 1.2% of the level inside the testicles. After three weeks of testosterone injections, LH and FSH fell to 5% and 3% of baseline, and intratesticular testosterone fell by 94% (Coviello et al., JCEM 2005).

That is why a man on TRT can feel better and have a high testosterone result while producing very little sperm. A literature review calls exogenous testosterone a preventable cause of male infertility for this reason (Transl Androl Urol 2013).

How often does it happen?

The clearest numbers come from male contraception research. In a World Health Organization trial, 271 healthy, fertile men took testosterone enanthate 200 mg weekly. By six months, 65% had no sperm in three consecutive semen samples (azoospermia), and the average time to reach zero was about 120 days (WHO Task Force, Lancet 1990).

These were healthy young men on a dose chosen to suppress sperm, so the figure is not a direct estimate for men on TRT for low testosterone. It still shows that suppression is common but not universal: about a third of the men in that trial still had sperm at six months.

So TRT is not birth control. If you and your partner do not want a pregnancy, use an established contraceptive method.

Who should not start TRT?

The guidelines are consistent on this point:

• "Exogenous testosterone therapy should not be prescribed to men who are currently trying to conceive" (AUA statement 23, Strong Recommendation, Grade A) (AUA 2018).
• The Endocrine Society recommends against starting testosterone in men "planning fertility in the near term" (Endocrine Society 2018).
• The male infertility guideline goes further: "For the male interested in current or future fertility, clinicians should not prescribe exogenous testosterone therapy" (AUA/ASRM 2020).

For men who may want children later, the AUA says the long-term effect of testosterone on sperm production should be discussed before treatment (statement 16, Strong Recommendation, Grade A) (AUA 2018). Low testosterone symptoms can still be treated. The plan may need to raise your own testosterone production instead of replacing it.

What are the options if you want to keep your fertility?

The AUA says clinicians "may use aromatase inhibitors, human chorionic gonadotropin, selective estrogen receptor modulators, or a combination thereof" in men with low testosterone who want to maintain fertility (statement 27, Conditional Recommendation, Grade C) (AUA 2018). A conditional recommendation with Grade C evidence means the supporting studies are limited. None of these drugs is FDA-approved for this purpose.

hCG

Human chorionic gonadotropin (hCG) acts like LH and stimulates the testicles to make testosterone. Its labeled uses in men are undescended testicles in boys and selected cases of hypogonadotropic hypogonadism (low testosterone caused by the pituitary); use alongside TRT is not on the label (hCG label).

Clomiphene and enclomiphene

These are selective estrogen receptor modulators (SERMs). They block estrogen's feedback in the brain, so the pituitary releases more LH and FSH. Clomiphene is FDA-approved for ovulation problems in women and is used off-label in men (Expert Opin Pharmacother 2016). A 2022 meta-analysis of 19 studies (4 randomized trials, 15 observational) found that clomiphene raised testosterone, LH, and FSH in men with low testosterone, with side effects reported in fewer than 10% of men (Andrology 2022). Enclomiphene is one of the two forms that make up clomiphene, and it is not approved by the FDA (BSSM position statement, 2026).

Aromatase inhibitors

Aromatase inhibitors such as anastrozole lower the conversion of testosterone to estradiol. Anastrozole is approved only for breast cancer in postmenopausal women (Arimidex label). In a one-year randomized trial in 69 men aged 60 and over with low or borderline testosterone, anastrozole lowered spine bone density compared with placebo (Burnett-Bowie et al., JCEM 2009). A review of TRT and fertility concluded that routine use of aromatase inhibitors "is not recommended based on a lack of long-term data" (Transl Androl Urol 2013).

Does adding hCG to TRT protect sperm?

The evidence is small. In the 2005 trial above, low-dose hCG kept intratesticular testosterone near normal during three weeks of testosterone injections, but the study measured testicular hormone levels, not sperm (Coviello et al., JCEM 2005). A retrospective review of 26 men on TRT plus hCG found that none became azoospermic, and 9 contributed to a pregnancy during follow-up; it had no comparison group (Hsieh et al., J Urol 2013).

That is not enough to treat hCG as a guarantee. It also does not change the guideline for men trying to conceive now: testosterone should not be prescribed to them (AUA statement 23). If you are on TRT plus hCG, only a semen analysis shows whether you are still producing sperm.

What side effects does hCG have?

The hCG label lists headache, irritability, restlessness, depression, fatigue, fluid retention (edema), breast tissue growth (gynecomastia), and pain at the injection site. It advises caution in people with heart or kidney disease, epilepsy, migraine, or asthma because androgens can cause fluid retention (hCG label).

hCG raises estradiol as well as testosterone. A randomized trial in 40 older men noted that hCG "increases not only circulating testosterone but also estradiol and other testicular steroids" (Liu et al., JCEM 2002). The label gives no rates for these side effects, and no study in men on TRT plus hCG has measured them well. It also means another injection on top of testosterone.

Can fertility come back after stopping TRT?

Usually, but it can take a year or more, and recovery is not certain.

In a pooled analysis of 1,549 healthy men from hormonal contraception trials, the chance of sperm concentration recovering to 20 million/mL was 67% within 6 months, 90% within 12 months, and 100% within 24 months. Recovery was faster with shorter treatment, shorter-acting preparations, and higher sperm counts at baseline (Liu et al., Lancet 2006). These men had normal testosterone and were in contraception trials, so the numbers may not apply to men treated for low testosterone.

Men who come to a fertility clinic after testosterone use can do worse. In a retrospective study of 66 such men who stopped testosterone and took hCG plus a SERM, 70% reached a total motile sperm count above 5 million within 12 months. Older age and longer testosterone use made recovery less likely (Kohn et al., Fertil Steril 2017). Another retrospective study of 77 men with past testosterone use found that 74% improved their sperm concentration on hCG plus FSH (Fertil Steril 2025). Neither study had an untreated comparison group.

Stopping testosterone a few months before trying to conceive is therefore not a reliable plan. Do not stop TRT or start fertility drugs on your own; work out the timing with the clinician managing your care.

How do you find out whether TRT has affected your fertility?

A semen analysis. The male infertility guideline calls for one or more semen analyses at the first evaluation, and hormone tests including FSH and testosterone in men with low sperm counts, low libido, erectile dysfunction, small testicles, or other signs of a hormone problem (AUA/ASRM 2020). A blood testosterone result, how you feel, and how much you ejaculate cannot tell you your sperm count.

The same guideline says both partners should be evaluated at the same time. It defines infertility as no pregnancy within 12 months when the female partner is under 35, and within 6 months when she is over 35 (AUA/ASRM 2020).

What to ask before starting TRT

If biological children are a possibility, raise it before your first dose. Useful questions:

1. Should I have a semen analysis first, so there is a baseline to compare against?
2. Is sperm banking worth doing before I start?
3. Given my labs and the cause of my low testosterone, is an option that keeps my own production going, such as a SERM or hCG, appropriate for me?
4. If I want to conceive later, what would the plan for stopping and recovery look like?

Frequently asked questions

Can you get someone pregnant while on testosterone?

Yes. In the WHO contraception trial, about a third of healthy men on weekly testosterone injections still had sperm after six months (WHO Task Force, Lancet 1990). Testosterone should not be used as birth control.

Is infertility from TRT permanent?

Usually not, but recovery can take more than a year and is not guaranteed. Older men and men with longer testosterone use recover less often (Kohn et al., Fertil Steril 2017).

Can sperm be tested while you are on TRT?

Yes. A semen analysis can be done while you are on testosterone, and it is the direct way to see how treatment is affecting sperm production.

Should men who want children later avoid TRT?

The male infertility guideline says clinicians should not prescribe testosterone to men interested in current or future fertility (AUA/ASRM 2020). If you still choose TRT, discuss baseline testing, sperm banking, and the alternatives first.

Bottom line

TRT lowers sperm production in many men, sometimes to zero, while blood testosterone looks fine. Men trying to conceive should not be prescribed testosterone, and men who want children later should discuss fertility before starting. Sperm production usually returns after stopping, but it can take a year or more and is less certain with age and longer use. hCG, SERMs, and aromatase inhibitors are options backed by limited evidence, and none is FDA-approved for this use.

AlphaMD providers review your labs before prescribing; you can read more about testosterone replacement therapy at AlphaMD.