It is one of the more common conversations in a men’s health clinic, and one of the most avoidable. A man in his thirties has been on testosterone for a year or two — prescribed for genuine deficiency, or obtained through a clinic or a gym — and he and his partner have decided to have a child. Nothing is happening. A semen analysis is ordered and comes back showing very few sperm, or none at all.
The surprise is almost universal, and it is understandable. Testosterone is the male hormone, associated with virility in every piece of marketing attached to it. That it shuts down sperm production is entirely counterintuitive, and a great many men are never told.
Why Testosterone Suppresses Fertility
The system runs on feedback. The brain monitors testosterone levels in the blood and adjusts its signalling accordingly: the pituitary gland releases luteinising hormone, which tells the testicles to produce testosterone, and follicle stimulating hormone, which drives sperm production.
When testosterone is supplied from outside the body, the brain reads the high blood level and concludes that no further signalling is needed. It reduces both hormones. The drop in LH means the testicles stop producing their own testosterone, and the drop in FSH means sperm production falls away with it. Sperm development also depends on a testosterone concentration inside the testicle far higher than anything achievable in the bloodstream, and that internal concentration collapses once local production stops. This is why an injection or gel cannot substitute — the hormone is present in the blood but absent where it is needed.
The effect is reliable enough that testosterone has been studied as a male contraceptive. Testicular shrinkage over months of treatment is the visible sign of the same process. This is not a rare side effect or a matter of individual susceptibility; it is how the drug works.
Recovery, and Why It Is Not Guaranteed
For most men, sperm production returns after stopping testosterone, but recovery is slow. It generally takes many months, and in some cases longer than a year, before counts return to baseline. The duration of treatment, the dose used and a man’s age and underlying testicular function all affect how quickly and how completely it happens.
In a minority of men, recovery is incomplete or does not occur. Long courses at high doses, particularly anabolic steroid use rather than physiological replacement, carry the greater risk. That possibility is the reason a man who might want children should not start testosterone without discussing it first, and the reason storing a semen sample beforehand is worth considering.
Where a man is already on testosterone and wants to conceive, a fertility-focused plan can be put together. This usually involves stopping the testosterone and using medications that restart the body’s own signalling — agents that stimulate the pituitary or mimic LH directly — alongside serial semen analyses to track recovery. It takes patience, and it works in a good proportion of cases.
Alternatives Where Fertility Matters
Not every man with low testosterone needs testosterone therapy, and this is worth knowing before treatment begins. Where the deficiency originates in the brain’s signalling rather than in the testicles themselves, medications that stimulate the body’s own production can raise testosterone while preserving or even improving sperm production. That approach is not right for everyone, but for a man of reproductive age it is frequently the better starting point.
Correcting the reversible contributors also matters and is often overlooked: untreated sleep apnea, significant excess weight, heavy alcohol use, opioid medications and poorly controlled diabetes all lower testosterone, and addressing them can raise it without any hormone at all.
The practical point is that this decision is easier to get right at the beginning than to unwind afterwards. A man starting testosterone should be asked whether he may want children, and if nobody has asked, it is a reasonable thing to raise yourself.
Dr. Raymond Nash assesses testosterone deficiency, male fertility and hormone treatment options at Grande Prairie Men’s Medical Clinic. Appointments can be booked through gpmm.clinic or by telephoning (587) 416-8296. The information above is general and is not a substitute for an individual assessment of your own hormone and fertility situation.