Skip to content

If you have low T, you may find that it stalls your sex drive. It can also contribute to erectile dysfunction, although there are other causes of ED.

Testosterone replacement therapy (TRT) can bring your testosterone levels back to normal and restore your sex drive.

But if you want to have children, there's one downside to TRT you should know about. It gives you back your sex life, but it might also reduce your ability to father children as long as you're on it.

"Testosterone replacement therapy has a profound impact on a man's reproductive potential," says urologist Michael Eisenberg, MD. He's director of male reproductive medicine and surgery at Stanford Hospital and Clinics in Palo Alto, Calif.

"In fact," Eisenberg says, "it's been studied as a method of birth control, because 90% of men can drop their sperm counts to zero while on testosterone. By increasing testosterone, you're not going to increase fertility."

Testosterone and Fertility

Testosterone plays an important role in making sperm.

Eisenberg describes the relationship between testosterone and sperm production as part of a "feedback loop." Here's how the system works.

Your brain makes special hormones, called gonadotropin-releasing hormones (GnRH). These hormones signal the testes to make more testosterone, vital for a healthy sperm count.

When you're getting testosterone replacement therapy, testosterone is added into the bloodstream by patches, gels, or other treatment methods.

Your brain interprets this rise in testosterone levels as a sign that you now have enough testosterone. So it stops sending signals to the testes to make more testosterone. But when your testes don't make more testosterone, your sperm production goes down.

A low sperm count makes it harder to conceive a child.

"If you have any kind of reproductive goal, you should not be using TRT," says Eisenberg.

Endocrinologist Spyros Mezitis, MD, PhD, agrees. "You want to increase the patient's own testosterone production in order to get an appropriate sperm sample for pregnancy," says Mezitis, who practices at Lenox Hill Hospital in New York City. "When testosterone comes from the outside, it suppresses the body's production of sperm."