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Last updated: Apr 24, 2020
1 min read

What are the side effects of TRT?


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

Testosterone replacement therapy (TRT) is a way to increase testosterone levels and treat the symptoms of low testosterone. However, one of the most common side effects of testosterone replacement therapy is low sperm count. But why?

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Testosterone and sperm production

Testosterone production is a feedback loop. When your brain senses low testosterone levels in your blood, it releases two chemicals: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH stimulates the production of testosterone in the testicles. FSH is essential for sperm production.

When you add external testosterone into the body, such as with TRT, your brain slows the release of both LH and FSH (because it thinks you don’t need them anymore). But since FSH is responsible for sperm production in the testicles, decreased FSH means decreased sperm count.

Other effects of TRT

In addition to decreased sperm count, other adverse effects of TRT include increased risk of cardiovascular events, increased prostate-specific antigen (PSA) levels with unclear effects on the prostate, and increased red blood cell count (Grech 2014). If you have low testosterone, talk to a healthcare provider to find out if TRT is right for you. Together, you can work to find the right dose to make sure any side effects are minimized.


  1. Grech, A., Breck, J., & Heidelbaugh, J. (2014). Adverse effects of testosterone replacement therapy: an update on the evidence and controversy. Therapeutic Advances in Drug Safety, 5(5), 190–200. doi: 10.1177/2042098614548680. Retrieved from