Testosterone is the most important male sex hormone and influences a multitude of processes in the body – from muscle mass to bone density. However, it is particularly essential for male fertility.
It regulates sperm production (spermatogenesis), libido, and overall sexual health. A hormonal imbalance can therefore have a significant impact on fertility ( Walker, 2011 ).
How testosterone affects fertility
Optimal testosterone levels are essential for spermatogenesis—the process of sperm production ( Papanikolaou et al., 2022 ). Low testosterone levels can lead to reduced sperm count, decreased libido, and erectile dysfunction ( Tsujimura, 2013 ). These factors impair the ability to conceive naturally. Additional symptoms may include loss of muscle mass, hair loss, and mood swings.
Testosterone and sperm production
Sperm production takes place in the testes and is controlled by a complex interplay of hormones ( Hauger et al., 2022 ). Three messenger substances in particular play a central role in this process:
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Gonadotropin-releasing hormone (GnRH) : This hormone is released in the hypothalamus and stimulates the pituitary gland to produce other hormones (LH & FSH).
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Luteinizing hormone (LH) : Stimulates the so-called Leydig cells in the testes to produce testosterone.
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Follicle-stimulating hormone (FSH) : Together with testosterone, it promotes the development of sperm in the seminiferous tubules of the testes.
A healthy testosterone level is therefore necessary to ensure sufficient sperm production. If the testosterone level drops too low, spermatogenesis is disrupted, which can lead to a lower sperm count, reduced sperm quality, and decreased fertility ( Walker, 2011 ).
Impact on libido and sexual health
Testosterone is not only responsible for physical sperm production, but also for sexual arousal and performance . Low testosterone levels can lead to the following problems:
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Decreased libido : Men with low testosterone levels often report a decrease in sexual desire ( Catena et al., 2024 ).
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Erectile dysfunction : Testosterone is necessary for the production of nitric oxide (NO), which relaxes blood vessels and enables an erection. A deficiency can therefore impair the quality of an erection ( Isidori et al., 2013 ).
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Ejaculation problems : A hormonal imbalance can lead to altered ejaculation patterns, such as delayed or absent ejaculation ( Tsujimura, 2013 ).
Learn more about the causes of erectile dysfunction and the available treatment options in our article “ Erectile Dysfunction: A Matter of the Mind or a Health Warning Sign? ”.
Hormonal imbalance and its consequences for fertility
Too high or too low a testosterone level can impair fertility in various ways:
Too low testosterone levels :
- Low sperm count and reduced sperm motility
- Decrease in sexual activity, which reduces the likelihood of successful fertilization.
- Increased fatigue and depressive moods, which negatively impact overall quality of life ( Vartolomei et al., 2018 )
Through exogenous testosterone administration such as TRT :
- Suppression of the body's own hormone production through so-called negative feedback (HPTA axis) ( Desai et al., 2022 )
- Reduced FSH and LH levels, which can lead to an almost complete cessation of sperm production.
- Possible shrinkage of the testicles due to insufficient stimulation of the Leydig cells ( Palacios et al., 1981 )
A delicate balance
Testosterone is a key factor in male fertility, but its influence is multifaceted. Too low a testosterone level can impair sperm production, while uncontrolled testosterone levels can also significantly reduce fertility . Therefore, careful hormonal balance is crucial – especially for men who wish to have children.
Later in this article, we will discuss which alternatives to testosterone therapy exist that can preserve fertility, and what the latest scientific findings are regarding the use of testosterone as a potential "pill for men".
Testosterone therapy and its effects on fertility
In men diagnosed with testosterone deficiency, testosterone therapy (TRT) can help normalize hormone levels and alleviate symptoms such as fatigue, decreased libido, and depressive moods. If there is a desire to have children, therapy should be carefully evaluated:
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Suppression of sperm production : External administration of testosterone can inhibit the body's own hormone production, leading to a significant reduction or even complete cessation of sperm production ( Desai et al., 2022 ).
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Testicular shrinkage : External hormone administration can lead to a shrinking of the testicles, which further impairs fertility ( Palacios et al., 1981 ).
Therefore, testosterone therapy is contraindicated in women with a desire to have children ( Patel et al., 2018 ).
The good news is that these impairments of fertility are usually reversible ( Bang et al., 2013 ). After discontinuing testosterone therapy, sperm production typically returns to normal within 4 to 6 months ( Handelsman et al., 2022 ). However, long-term or abusive use of high doses of testosterone can impair fertility recovery. There is evidence that misuse, particularly at significantly higher doses than prescribed for testosterone replacement therapy (TRT), can lead to permanent fertility impairment ( Osta et al., 2016 ).
Therefore, men who currently wish to have children should only consider testosterone therapy within the next 6 months after careful consideration and under strict medical supervision.
Alternative treatment approaches
For men wishing to have children, there are alternative treatment approaches that aim to stimulate the body's own testosterone production without affecting sperm production. Two of these approaches are the use of selective estrogen receptor modulators (SERMs) such as clomiphene and tamoxifen, and the administration of human chorionic gonadotropin (hCG).
Selective estrogen receptor modulators (SERMs): Clomiphene and Tamoxifen
SERMs work by blocking estrogen receptors in the hypothalamus. This tricks the body into thinking estrogen levels are low, leading to an increased release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland. This stimulates the Leydig cells in the testes to produce more testosterone , while spermatogenesis is maintained ( Rambhatla et al., 2016 ).
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Clomiphene
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Clomiphene Clomiphene is frequently used in men whose testicles produce too little testosterone because the necessary signal from the brain is lacking. This can lead to reduced sperm count and quality. Clomiphene helps improve this process by boosting the body's own testosterone production. Studies show that treatment with clomiphene can increase sperm count and motility, thus improving the chances of natural conception. Because it is well-tolerated and supports the hormonal balance naturally, it is often chosen as a first-line treatment option ( Guo et al., 2019 ).
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Tamoxifen
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Tamoxifen also belongs to the group of SERMs and has a similar mechanism of action to clomiphene. However, while clomiphene can act as both an estrogen antagonist and agonist , tamoxifen exhibits a purely blocking effect on estrogen receptors. As a result, it can, in certain cases, cause a greater increase in the body's own testosterone levels than clomiphene. Studies suggest that tamoxifen may be a viable alternative to clomiphene, particularly in men with low testosterone levels and simultaneously reduced sperm quality ( Ide et al., 2020 ).
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A comparison of the two active ingredients shows that clomiphene is used more frequently because it is better researched and generally considered more effective. However, tamoxifen can be used in cases where clomiphene is not sufficiently effective or is not tolerated.
Human chorionic gonadotropin (hCG)
hCG is a hormone structurally similar to luteinizing hormone (LH). In men, hCG administration can directly stimulate the Leydig cells in the testes to produce more testosterone ( Madhusoodanan et al., 2019 ). This can be particularly beneficial for men with hypogonadism (testosterone deficiency) who wish to have children, as hCG stimulates the body's own testosterone production without suppressing spermatogenesis ( Babak et al., 2018 ).
In some cases, hCG is used in combination with FSH (follicle-stimulating hormone) to optimize both testosterone production and sperm production. This combination therapy is primarily used in men with very low sperm concentrations ( Kobori et al., 2014 ).
Important instructions
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Off-label use: The use of clomiphene, tamoxifen, and hCG to treat male infertility often occurs outside of their approved indications ( "off-label use" ). Therefore, these therapies should only be carried out under careful medical supervision and after comprehensive patient education.
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Individual consultation: Not every man wishing to have children is suitable for these therapies. Thorough diagnostics and individual consultation with an experienced doctor are essential to create the optimal treatment plan.
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Support from Adon Health: At Adon Health , we offer specialized hormone tests that allow you to precisely analyze your testosterone and hormone levels. This provides you with a sound basis for medical decisions and enables you to develop a tailored therapy together with experienced doctors.
These alternative therapeutic approaches can improve fertility in men who wish to have children, without risking the negative effects of external testosterone administration on sperm production .
Testosterone as a potential contraceptive for men
The development of a "male contraceptive pill" as a hormonal contraceptive has been a research topic for decades. The goal is to suppress sperm production to prevent conception. Although various approaches have been investigated, no male contraceptive is currently available on the market. Side effects of the tested hormonal or non-hormonal medications often prevent their approval ( Louwagie et al., 2023 ).
Hormonal approaches:
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Testosterone and progestins: Previous studies focused on combining testosterone with progestins to inhibit sperm production. This combination affects the feedback loop between the hypothalamus, pituitary gland, and testes, leading to the suppression of sperm production. However, these approaches were not pursued further due to side effects and insufficient efficacy ( Büchter et al., 1999 ).
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Dimethandrolone undecanoate (DMAU): Another hormonal drug that has been investigated is DMAU. It combines androgenic and progestogenic properties and is intended to reliably suppress sperm production. In studies, side effects such as loss of libido and weight gain were rare. However, long-term studies are still needed to fully evaluate the potential of this approach ( Thirimalai et al., 2020 ).
Non-hormonal approaches:
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TDI-11861: This drug blocks an enzyme responsible for sperm motility. In animal studies, TDI-11861 led to complete but reversible infertility within 30 to 60 minutes. Sperm motility was restored after 24 hours. Further clinical trials are needed to confirm efficacy and safety in humans ( Balbach et al., 2023 ).
Developing a safe, effective, and reversible contraceptive method for men remains a challenge. While some approaches show promise, further research is needed to enable their use in everyday clinical practice.
Our conclusion, your knowledge
Testosterone is essential for male fertility, but an imbalance can severely impair fertility. While testosterone replacement therapy (TRT) can alleviate symptoms of a deficiency, it suppresses sperm production and is not suitable for men who wish to have children .
The good news: In most cases, this impairment is reversible if countermeasures are taken in time. Alternatives such as clomiphene, tamoxifen, or hCG can help increase the body's own testosterone production without jeopardizing fertility.
Besides its role in reproduction, testosterone is also being researched as a male contraceptive – whether as a gel or pill . While initial studies are promising, further research is needed.
🔍 Adon Health helps you analyze your hormone levels and find the best solution for your health.
