This is the conversation I least want a man to have after the fact. Testosterone therapy is effective, but conventional TRT can meaningfully suppress fertility — and too many men learn that only once they are trying to conceive.
Why It Happens
Your brain monitors circulating testosterone and adjusts its signaling accordingly. When testosterone arrives from outside the body, the brain reads the level as sufficient and dials down the hormones that instruct the testes to keep working. Sperm production depends on that internal signal, not on the testosterone in your bloodstream. Turn the signal down and production falls with it.
Testicular size often decreases as well, for the same reason.
Is It Reversible?
Frequently, yes — sperm production often recovers over months after stopping, though timelines vary considerably between individuals and recovery is not guaranteed. Duration of therapy, age, and baseline fertility all influence the outcome. "Usually reversible" is an honest answer; "always reversible" is not.
What the Options Look Like
- Delay therapyIf conception is planned in the near term, waiting is sometimes the cleanest choice.
- Fertility-sparing approachesCertain protocols aim to raise testosterone while preserving the brain's signal to the testes.
- PreservationBanking sperm before starting removes the uncertainty entirely.
- Address the drivers firstSleep, weight, and metabolic health sometimes move testosterone enough to postpone the decision.
The Point Isn't to Scare You Off
It is to make sure the decision is yours, made with the full picture. Plenty of men proceed with therapy after weighing this and are glad they did. What matters is that nobody hands you a prescription without asking the question.
Have the Conversation
book a consultation to discuss your goals and timeline, take the 3-minute quiz, or read more about hormone therapy for men. Dr. Allen's book, Why Do I Feel Like This? covers the broader picture of male hormone health in depth.