Sauna and Testosterone: What the Research Actually Shows (2026)
By IceColdTubs · Updated August 6, 2026
Quick Answer: Sauna use does not reliably raise testosterone — the one study that found an increase (Kukkonen-Harjula et al., 1989) only saw it under extreme, exhaustion-level heat in 8 men, while a larger 2021 trial of 30 men found no significant change at all. What sauna does reliably do is lower cortisol (13.61 to 9.67 µg/mL, p<.001, Podstawski et al. 2021), which is an indirect, plausible-but-unproven path to better testosterone conditions over time. Separately, sauna heat has a well-documented, reversible negative effect on sperm count and motility (dropping more than 50% in one study) through local scrotal heating — a completely different mechanism from systemic testosterone that’s worth knowing if fertility is a concern.
“Does sauna boost testosterone” is one of the most repeated claims in heat-therapy content, usually pointing back to the same one small study without mentioning what it actually tested. Here’s what the research shows, what it doesn’t, and why sperm count and testosterone need to be treated as two separate questions.
The study behind the claim — and what it actually found
The testosterone-and-sauna claim traces mostly to Kukkonen-Harjula et al., published in the European Journal of Applied Physiology (1989). Researchers put 8 healthy young men through three different Finnish sauna conditions: 80°C dry heat, 100°C dry heat, and 80°C heat that became humid, each continued until subjective discomfort or exhaustion. Testosterone rose only in the third condition — the most physiologically stressful one, at 80°C with rising humidity pushed to exhaustion. It did not rise significantly in the 80°C dry or 100°C dry conditions. Cortisol, meanwhile, decreased at both 80°C and 100°C, and prolactin rose sharply (2-fold at 80°C dry, up to 10-fold at 80°C humid).
That’s a real, peer-reviewed finding — but an 8-person sample, with a testosterone effect that only showed up under the single harshest condition tested, is thin evidence for a blanket “sauna raises testosterone” claim. A more recent and better-powered study points the other way.
A larger, newer study found no testosterone change at all
Podstawski et al., published in the American Journal of Men’s Health (2021), studied 30 men aged 19-26 through four sauna sessions of 12 minutes each at 90-91°C, each followed by a brief cold-water immersion cool-down. Testosterone moved from 4.04 to 4.24 ng/mL — a change the researchers reported as not statistically significant (p>.05). Cortisol, on the other hand, dropped significantly: 13.61 to 9.67 µg/mL (p<.001).
Sauna Thermometer/Hygrometer
Why we like it: the studies above show testosterone and cortisol responses depend heavily on exact heat and humidity conditions — a thermometer/hygrometer combo lets you know what conditions you're actually training in, not just guess. See our best sauna thermometer picks for specific models.
Check Price on Amazon →The 15-20 minutes you spend logging heat and humidity readings pass a lot easier with something good in your ears — start a free Audible trial and get your first audiobook free.
Put the two studies side by side and the honest pattern is: testosterone barely moves in a normal sauna session, and the one positive result required pushing 8 men to exhaustion in humid 80°C heat — not a protocol most people replicate on a Tuesday evening.
The more reliable hormone story: cortisol, not testosterone
If there’s a defensible sauna-and-testosterone connection, it’s indirect. Cortisol and testosterone are regulated somewhat antagonistically in the body — chronically elevated cortisol is associated with suppressed testosterone production. Podstawski et al.’s significant cortisol drop (13.61 to 9.67 µg/mL) is a real, repeatable finding across multiple studies of sauna use. That gives a plausible mechanism for sauna supporting testosterone conditions over time by lowering a known suppressor — but it’s a mechanism, not a demonstrated outcome. No study in our search directly measured whether regular sauna-driven cortisol reduction translates into a measurably higher testosterone level months later.
Growth hormone rises reliably — but it’s a different hormone
The most consistently documented acute hormonal response to sauna heat isn’t testosterone — it’s growth hormone. Kukkonen-Harjula et al. (1989) recorded growth hormone increasing roughly 2- to 5-fold during a single session, with the largest rise at 100°C dry heat. Some of that spike is attributed to heat-induced dehydration and fluid-volume shifts rather than a pure endocrine-stimulation effect, so it’s a real, repeatable acute response worth knowing about — just not the same claim as “sauna raises testosterone,” even though the two get bundled together in a lot of wellness content.
| Hormone | What the research shows | Strength of evidence |
|---|---|---|
| Testosterone | Rose only under the most extreme condition in an 8-person study; no significant change in a 30-person study | Weak, inconsistent |
| Cortisol | Reliably decreases across sauna sessions | Consistent, repeatable |
| Growth hormone | Rises 2- to 5-fold acutely, partly dehydration-related | Consistent for the acute spike |
| Sperm count/motility | Drops more than 50% with repeated intensive sauna use, reversible | Consistent, different mechanism (local heat, not systemic hormone) |
Testosterone and sperm count are not the same question
This is where a lot of sauna-and-fertility content goes wrong: it treats “does sauna hurt sperm” and “does sauna hurt testosterone” as the same question, and they’re not. Sperm production happens in the testes, which need to stay 2-3°C below core body temperature to function normally. A study of 10 normozoospermic men who took two 15-minute sauna sessions per week at 80-90°C for 3 months found scrotal temperature rose by roughly 3°C during sessions, and sperm concentration and motility dropped by more than 50%, with altered sperm DNA packaging. That’s a real, meaningful effect — but it’s driven by local testicular heat exposure, not by a drop in circulating testosterone. The same study found sperm parameters recovering toward baseline roughly 6 months after the heat exposure stopped, so the effect is reversible rather than permanent.
If you’re actively trying to conceive, that’s a legitimate reason to dial back sauna frequency or duration for a while. It is not evidence that sauna use lowers your testosterone level.
Where cold plunge fits in
Cold exposure gets its own share of testosterone claims, most of them built on even thinner evidence than the sauna research above — we haven’t found a well-powered, sham-controlled study directly linking cold plunge to a measurable testosterone change. What cold-water immersion does have real evidence for is the noradrenaline and dopamine spike covered in our cold plunge benefits guide, which is a separate physiological effect from the sauna-and-hormones question here. If you’re weighing the two side by side more generally, our sauna vs cold plunge guide covers the broader tradeoffs.
Sauna and testosterone, by the numbers
- 4.04 to 4.24 ng/mL (p>.05). Testosterone change across 4 sauna sessions in 30 men, Podstawski et al. 2021 — not statistically significant.
- 13.61 to 9.67 µg/mL (p<.001). The same study’s cortisol drop — the more reliable hormonal finding.
- 2- to 5-fold. Growth hormone increase during a single Finnish sauna session, Kukkonen-Harjula et al. 1989.
- >50%. The drop in sperm concentration and motility after 3 months of twice-weekly intensive sauna sessions (Garolla et al., 2013) — a local-heat effect on fertility, distinct from testosterone.
The bottom line
- Sauna does not reliably raise testosterone — the one study showing an increase needed extreme, exhaustion-level heat in just 8 men; a larger 30-person study found no significant change.
- Cortisol reduction is the more consistent hormonal finding, and a plausible (but unproven) indirect path to better testosterone conditions over time.
- Growth hormone rises reliably and acutely during a sauna session, but that’s a different hormone from testosterone and partly reflects dehydration.
- Sperm count and testosterone are different questions — intensive sauna use can meaningfully (but reversibly) reduce sperm count and motility through local scrotal heating, independent of any change in circulating testosterone.
- If fertility is an active concern, dialing back sauna frequency is a reasonable precaution grounded in real data — not a sign your testosterone is at risk.
For a broader look at what sauna heat reliably does and doesn’t do, see our sauna for beginners guide, and for another hormone-adjacent question we’ve fact-checked, see our sauna and detox guide. Alcohol is a separate, better-documented testosterone suppressor than sauna heat — our sauna and alcohol guide covers why the two shouldn’t be mixed anyway. Wondering if heat affects hair the way it doesn’t reliably affect testosterone? Our sauna and hair loss guide covers the actual shedding research and the DHT connection.
🛒 Top Picks from This Guide
Browse all our picks →🔥 Today's deals →
Product prices and availability are accurate as of the date/time indicated on each product and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product. As an Amazon Associate we earn from qualifying purchases.