What are the side effects of testosterone replacement therapy (TRT)?

Acne, irritability, shrunken testicles

It can even shut down sperm production

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Disclaimer: This information isn’t a substitute for professional medical advice, diagnosis, or treatment. You should never rely upon this article for specific medical advice. If you have any questions or concerns, please talk to your doctor.

Testosterone replacement therapy side effects

Testosterone replacement therapy (TRT) is a common way to increase testosterone and treat the symptoms of low testosterone. But one of the most common side effects of testosterone replacement therapy is low sperm count. A risk of TRT is that artificially high testosterone levels can trick your brain into stopping LH and FSH production. And when you stop making FSH, you stop making sperm.

Testosterone and sperm production

Testosterone production is a feedback loop. When your brain senses low testosterone levels in your blood, it ramps up testosterone production in the testicles by releasing two hormones:

  • Luteinizing Hormone (LH) – Makes testosterone in the testicles
  • Follicle Stimulating Hormone (FSH) – Essential for sperm production

When you add external testosterone (from replacement therapy), your brain slows production of LH and FSH because it thinks you don’t need anymore. But FSH is directly responsible for sperm production in the testicles. Decreased FSH levels together with already low natural levels of testosterone can decrease your sperm count. A lot. In fact, men using Testosterone replacement therapy can have a sperm count in the semen of zero.

Low testosterone production in the testicles means low sperm count. But too much testosterone can mean the same thing. Many of the side effects of high testosterone—like acne and mood shifts—are reversible. But other long-term effects of TRT (particularly regarding sperm count and fertility) are unknown. Talk to a doctor to find out if testosterone replacement therapy is right for you. Then work to find the right dose to make sure your testosterone levels stay within normal levels to reduce your risk of side effects.

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