Sauna on testosterone: TRT, hematocrit, fertility and the hot room

Short answer: A sauna stays open on testosterone replacement therapy. TRT raises hematocrit, the red-cell count your prescriber monitors, and dehydration is the most common cause of a high reading, so drink before and after, keep sessions moderate and mention a heavy sweat before a blood test. TRT can suppress sperm production and regular sauna heat lowers it reversibly. No good evidence says heat or cold boosts testosterone.

A sauna, a hot tub and a cold plunge all stay open on testosterone replacement therapy; we found no study pointing to a direct interaction. The drug raises hematocrit, the share of your blood made of red cells, which labels and guidelines ask prescribers to monitor, and dehydration is the most common cause of a high reading: drink before and after, keep sessions moderate and tell your clinic about a heavy sweat before a blood draw. TRT can nudge blood pressure up slightly. If you want children, TRT can suppress sperm production and regular sauna heat reversibly lowers sperm counts, so raise fertility before you start. And no good evidence says the sauna or the plunge boosts testosterone.

This is general information, not medical advice. The dose, the formulation, the blood tests and what to do about a high result belong with your prescriber, and nothing here is a reason to start, stop or change testosterone.

What testosterone does to your blood, and why the sauna cares

The red-cell count is the number to know.

The Endocrine Society guideline by Bhasin and colleagues in the Journal of Clinical Endocrinology and Metabolism in 2018 states that testosterone “increases hemoglobin and hematocrit”, that the effect is related to dose and blood levels, and that in some men it can cause erythrocytosis, which it defines as a hematocrit above 54%.

The same guideline lists a hematocrit above 48% (above 50% for men living at high altitude) among the conditions in which it recommends against using testosterone. The American Urological Association guideline by Mulhall and colleagues in the Journal of Urology in 2018 asks clinicians to measure hemoglobin and hematocrit before treatment and to tell patients about the increased risk of polycythemia, a raised red-cell mass.

The AndroGel 1% prescribing information says to check hematocrit before starting and suggests re-checking three to six months in and then annually; if it climbs too high, therapy is stopped until it comes down. Its stated reason: “An increase in red blood cell mass may increase the risk of thromboembolic events”, meaning clots.

The sources frame the numbers differently, and the AUA statements we read set no threshold at all. The number that applies to you is the one your prescriber is working to.

Heat, sweat and the hematocrit reading on TRT

Dehydration concentrates the blood.

A hot room makes you sweat, and MedlinePlus lists sweating too much, for example from exercising in hot weather, as a cause of dehydration, with thirst, darker urine, dizziness and a rapid heartbeat among the signs. The MedlinePlus page on the hematocrit test goes further: dehydration, by lowering the plasma part of the blood, is “the most common cause of a high hematocrit”.

TRT raises the red-cell count, and dehydration concentrates what is there. We found no study measuring this in men on TRT in a sauna, but a long sweat on a drug whose label ties red-cell mass to clot risk is a good reason to drink before and after and keep sessions moderate.

It also matters for the number itself. A blood draw taken while you are dehydrated can read higher than your usual, and your prescriber makes decisions on that reading. Ask your clinic whether to avoid a heavy sauna or workout sweat before a blood test, and mention it if you had one.

The labels also warn about clots in the leg veins or lungs. The AndroGel label tells prescribers to evaluate a painful, swollen, warm or red leg for deep vein thrombosis, and sudden shortness of breath for pulmonary embolism. We found no evidence tying these to sauna use; they are symptoms never to blame on a long session.

Blood pressure and the heart on TRT: what the labels say

A small rise, and a trial that settled the bigger question.

In February 2025 the FDA announced class-wide labeling changes for testosterone products. Blood pressure monitoring studies “confirmed an increase in blood pressure with use of all testosterone products, class-wide”, so the agency required a blood pressure warning on products that lacked one, and it recommended removing boxed-warning language about an increased risk of adverse cardiovascular outcomes.

That removal followed the TRAVERSE trial, published by Lincoff and colleagues in the New England Journal of Medicine in 2023. In 5,246 men aged 45 to 80 with heart disease or high cardiovascular risk, major cardiac events occurred in 7.0% on testosterone gel and 7.3% on placebo, meeting the trial’s test for non-inferiority. Atrial fibrillation, acute kidney injury and pulmonary embolism were more common with testosterone.

The blood pressure changes are small. The AndroGel label reports mean rises of 1.9/1.3 mm Hg after 16 weeks in a monitoring study of the 1.62% gel, and 3.0/2.2 mm Hg in men already treated for hypertension. It also notes that androgens can promote retention of sodium and water.

If you also take blood pressure medication, the sauna exit is the moment that matters; our guides to feeling faint in a sauna and heat, cold and common medications cover it.

Sauna heat, sperm and fertility on TRT

Two separate brakes on the same system.

Garolla and colleagues in Human Reproduction in 2013 had ten healthy men take two 15-minute sessions a week at 80 to 90°C for three months. Sperm count and motility were strongly impaired at the end, with changes in sperm DNA packaging and mitochondrial function, while sex hormones did not change significantly.

Six months after the sessions stopped, every change had reversed. It was a small study of men with normal semen, and it measured sperm, not pregnancies. Our guide to sauna, hot tubs and sperm count adds the hot tub evidence, and our guide to heat while trying to conceive covers both partners.

Testosterone therapy is the other brake. The AndroGel label says that with large doses, spermatogenesis “may be suppressed through feedback inhibition” of the pituitary hormone FSH, and the Endocrine Society lists reduced sperm production and fertility among testosterone’s potential adverse effects. It recommends against testosterone in men planning fertility in the near term, and the AUA says testosterone “should not be prescribed to men who are currently trying to conceive”.

So on TRT, sauna heat is a second, reversible factor on top of a treatment that already bears on fertility. If you are considering TRT and want children, the AUA asks for a reproductive health evaluation before treatment and a discussion of testosterone’s long-term effect on sperm production. Our guide to sauna heat and male fertility covers the heat side.

Cold plunges on TRT

The same questions as anyone, with the heart in view.

Cold water sets off the cold shock response, which Shattock and Tipton in The Journal of Physiology in 2012 describe as a sympathetically driven tachycardia, a sudden racing heart. They also note that cold water submersion can trigger heart rhythm disturbances even in healthy volunteers.

For a healthy man on TRT with normal blood pressure, a plunge is the same decision as for anyone, and our guide to who should avoid cold plunging covers it. With high blood pressure, or any history of atrial fibrillation, which was more common on testosterone in TRAVERSE, icy immersion is a question for a cardiologist first. Keep your head above the water and never plunge alone.

Do saunas or cold plunges boost testosterone?

No, and on TRT the question is moot.

The claim that cold plunges raise testosterone does not hold up, and our guide to whether cold exposure raises testosterone goes through why. The sauna version fares no better: in the Garolla study, three months of regular sessions changed sperm sharply and sex hormones not significantly.

On TRT your level is set by the prescription and checked with blood tests, and nothing we found suggests a hot or cold room changes that.

Testosterone gel, massage and the spa

The transfer rule matters most here.

The AndroGel 1% label says to avoid showering, swimming or bathing for at least five hours after applying, to let the site dry and then cover it with clothing, and to avoid fire, flames or smoking until it dries, because the gel is alcohol-based and flammable. It does not mention saunas, but a session that ends in a shower or a plunge falls under that rule, so check the wait on your own product’s label.

Its boxed warning is about other people: children have developed virilization after secondary exposure to testosterone gel, and the label says they “should avoid contact with unwashed or unclothed application sites”. A family sauna, a hot tub or a massage table is where bare skin meets skin, and the label’s instruction is to wash the site thoroughly with soap and water before expected skin-to-skin contact.

The AUA guideline asks clinicians to discuss that transference risk with gel users. Tell a massage therapist, and wash first. Otherwise massage, yoga, floats and classes have no interaction with testosterone that we found.

Testosterone and wellness at a glance

Situation	Fine as is	Needs adjusting	Avoid
Sauna, steam, hot tub	With water before and after	Moderate sessions, not stacked on a hard sweaty workout	Long, dehydrating sessions
Blood test day	Tell the clinic about recent heavy sweating	Ask whether to skip a big sweat beforehand	A hard sauna session right before the draw, unmentioned
Cold plunge	Cool showers, gentle formats	Cardiologist’s view with high blood pressure or atrial fibrillation	Alone, head under, or through chest pain
Testosterone gel at the spa	Dry, covered site	Check your label’s shower wait; wash the site before massage	An unwashed site against a child’s or partner’s skin
Trying to conceive, or planning to	Talk to your prescriber first	Pausing regular heat is reversible	Assuming TRT and sauna habits do not matter

What is oversold about testosterone and the sauna

The hormone boost, and the clinic without blood tests.

The testosterone-boosting sauna and plunge come first. Neither is supported, and on TRT both are irrelevant.

The second is TRT sold as a performance upgrade with the blood work treated as optional. The Endocrine Society builds treatment around testing: diagnosis only with symptoms and consistently low morning testosterone, confirmed by a repeat measurement, and monitoring of testosterone and hematocrit once treatment starts. A service that skips those is offering something other than what the guidelines describe. Our guide to spotting a nonsense wellness claim is the filter.

What belongs to your prescriber on TRT

The dose, the formulation, the blood tests, and the fertility question.

The dose, the formulation, the blood test schedule and what happens if your hematocrit climbs belong with the prescriber. Ask about a regular sauna or hot yoga habit and how to time blood draws around it, about cold plunging if you have high blood pressure or a heart rhythm problem, and about fertility before you start.

Seek urgent care for a painful, swollen, warm or red leg, sudden shortness of breath, chest pain, or a faint with an injury. We only recommend what we would send a friend to, and here that means a venue with water by the sauna door and a shower to wash an application site.

In our medication heat-warning label index, the FDA label for AndroGel 1.62% uses none of the heat, sweating, dehydration or sun-sensitivity terms we searched for. That is not the same as saying it is safe in heat; it means the label does not address it.

FAQ: sauna on testosterone

Can I use a sauna on testosterone replacement therapy? Yes, with water before and after and moderate sessions. We found no study of the combination; the care is because TRT raises hematocrit and dehydration pushes the reading higher.

Does a sauna raise hematocrit on TRT? Nobody we found has measured it. Dehydration is the most common cause of a high hematocrit reading, so a heavy sauna sweat could push the number up temporarily; ask your clinic whether to avoid one before a blood test.

Does sauna heat affect fertility on TRT? Regular sauna use reversibly lowered sperm count and motility in a small study, and TRT itself can suppress sperm production. If you want children, raise it with your prescriber before starting TRT.

Do saunas or cold plunges boost testosterone? No good evidence says so, and in the sauna study sex hormones did not change significantly. On TRT, your level is set by the prescription.

Does testosterone cause heat intolerance? The AndroGel 1.62% label in our index uses none of the heat, sweating, dehydration or sun terms we searched for, so heat intolerance is not among its listed side effects. That is not the same as saying heat carries no risk on TRT: the care in a sauna is about hematocrit, which TRT raises and dehydration pushes higher, so drink water before and after.

The bottom line on sauna and testosterone

A sauna stays open on TRT. The drug raises hematocrit, which your prescriber monitors, and dehydration is the most common cause of a high reading, so drink, keep sessions moderate and mention heavy sweating before a blood test.

TRT can suppress sperm production and regular sauna heat reversibly lowers it too, so fertility belongs in the conversation before treatment starts. Gel users should wash the site before skin meets skin.

A painful swollen leg, sudden breathlessness or chest pain belong with urgent care, and the dose and the numbers belong with the prescriber.