Testosterone Replacement Therapy (TRT) has become an increasingly popular solution for men dealing with low testosterone, also known as hypogonadism. From increased energy to a stronger sex drive, TRT can significantly improve quality of life as well as certain biomarkers of health. But for men who want to have biological children—now or in the future—there’s a critical issue that often gets overlooked: Testosterone can drastically suppress your fertility.
If you’re weighing the pros and cons of TRT, it’s vital to understand the potential impact on your reproductive system. In this blog, we’ll explain why exogenous testosterone affects sperm production, how common it is, what the recovery process looks like, and most importantly, what you can do to protect your ability to conceive.
Why Synthetic Testosterone Impacts Sperm Production
To understand how testosterone therapy affects fertility, you have to look at how the body regulates hormone production. The body relies on a feedback loop called the hypothalamic-pituitary-gonadal (HPG) axis, which controls testosterone and sperm production.
Here’s what happens under normal conditions:
- The hypothalamus in the brain releases gonadotropin-releasing hormone (GnRH) in a pulsatile manner
- GnRH signals the pituitary gland to release two hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH)
- LH stimulates the testicles to produce testosterone
- FSH promotes sperm production in the testes
- Some testosterone is converted into estrogens which feedback on the pituitary gland and hypothalamus signaling adequate hormone levels and closing the loop
When you start TRT using exogenous testosterone, however, you’re introducing testosterone into the system. Your brain interprets this as a signal that you’re producing plenty of testosterone on your own, so it shuts down LH and FSH production. As a result:
- Your body stops producing natural or endogenous testosterone
- Your testes shrink and stop producing sperm
- Over time, this can lead to low sperm count (oligospermia) or complete absence of sperm (azoospermia)
This process can begin within weeks of starting TRT and is the most common cause of infertility in young men seen by urologists.
How Common Is Infertility on TRT?
Infertility from TRT is not a rare side effect; it’s common and expected. Clinical research shows that up to 90% of men on testosterone therapy will experience a significant reduction in sperm count, and many will become completely infertile while on treatment.
The degree of infertility can vary based on:
- The form of TRT used (injections, gels, pellets, etc.)
- The dosage and duration of treatment
- The age and baseline fertility of the individual
- Whether adjunct medications like hCG are used concurrently
Some men may continue to produce some sperm, but it’s typically not enough to achieve pregnancy without medical intervention. For many, natural conception becomes extremely difficult or impossible. This effect can be intermittent or “hit or miss” in some men. Therefore, testosterone therapy is NOT a form of birth control.
Options for Preserving or Restoring Fertility
If you’re thinking about TRT but want to keep your options open for fatherhood, you’re not out of luck. There are ways to preserve or maintain fertility while still addressing low testosterone symptoms.
1. Sperm Banking (Cryopreservation)
Before starting TRT, consider freezing your sperm. This gives you a backup plan if fertility is impacted and you want biological children later. Keep in mind that frozen sperm will require assisted reproductive technologies to achieve a pregnancy. This means your partner will have to go through IVF which is expensive and not without medical risks.
2. Clomiphene Citrate (Clomid) and enclomiphene
Clomid is a selective estrogen receptor modulator. It’s an oral medication that blocks the estrogen receptors at the level of the pituitary gland. This blocks the negative feedback loop we mentioned earlier to stimulate the release of LH and FSH by the pituitary gland. This LH and FSH surge will promote an increase in testosterone production by the testicle and have a positive effect on spermatogenesis. Clomid is FDA approved to treat anovulation in women but it has been used off-label by urologists for decades to treat hypogonadism in men who wish to father children. It is also used to treat hormonal causes of oligospermia.
Enclomiphene is one of the two isomers found in Clomid. It is not FDA approved to treat anything in men or women so it must be compounded. It is thought to have fewer side effects than Clomid according to some small studies.
3. hCG (Human Chorionic Gonadotropin)
hCG is an injectable medication that is biochemically similar to LH. It basically serves as an LH analogue that binds to the Leydig cells in the testicle to promote endogenous testosterone production. Human chorionic gonadotropin can be used alone to treat low testosterone in men who wish to father children since it has no adverse effect on fertility. hCG can also be given along with exogenous testosterone in order to maintain some degree of endogenous testosterone production. This can help maintain spermatogenesis in men using synthetic testosterone but it doesn’t work in everyone.
4. FSH Therapy
In more advanced fertility treatment plans, injectable FSH can be added to help stimulate sperm production directly in men who have become oligo or azoospermic due to TRT.
What to Do If You’re Already on TRT
If you’ve already started TRT and are now thinking about starting a family, don’t panic. Many men are able to restore fertility with aggressive medical intervention. The most important step is to consult a urologist who can evaluate your fertility and hypogonadism properly. Urology is the only speciality in medicine with expertise in both male infertility and hypogonadism.
Expect the process to take time; in some cases 12-24 months to restore sperm production. Also keep in mind that some men can be rendered infertile forever despite heroic medical efforts to restore fertility.
Consult the Experts at Obsidian Men’s Health
TRT can be life-changing, but it’s not a one-size-fits-all solution. If fatherhood is on your horizon, you need a treatment plan that supports both your hormonal health and your fertility goals. At Obsidian Men’s Health, we specialize in helping men find the right balance through expert evaluation, fertility-preserving protocols, and ongoing support. Whether you’re just starting to consider TRT or have already begun treatment, we’ll help you build a plan that aligns with your health goals, lifestyle, and future family plans.
Take control of your sexual health. Request a consultation with Obsidian.
