Thermal & cold · graded by use, five uses
Traditional Finnish Sauna (dry sauna)
Graded on: blood pressure and cardiorespiratory fitness when sauna follows exercise; headache pain (self-report).
Grade C: human trials exist, but they are small, mixed or not yet repeated. This is not a finding that it does not work. How to read a grade →
At a glance
A traditional Finnish sauna is a hot wooden room heated by a stove, with dry air at about 80 degrees Celsius. Large studies in Finland found that men who used a sauna most often had fewer heart deaths and less dementia, but those studies only show a link. In small trials, a sauna after exercise lowered blood pressure more than exercise alone. A sauna on its own did not change blood vessel health in people with heart disease. Headache pain eased a little in one small study. Breathing hot sauna air did not ease cold symptoms.
The C is shared by two of the five uses graded on this record, each on its own evidence. The other three carry their own letters.
As studied, and the trials
Lee et al. (Am J Physiol Regul Integr Comp Physiol, 2022; PMID 35785965): 47 sedentary adults with a cardiovascular risk factor, randomized to exercise plus 15 minutes of sauna, exercise alone or no change for 8 weeks; adding sauna lowered systolic pressure by 8 mmHg more than exercise alone (95% CI -14.6 to -1.4) and raised VO2max The most oxygen the body can use during all-out exercise, a standard measure of aerobic fitness. by 2.7 mL/kg/min more. Gayda et al. (J Clin Hypertens, 2012; PMID 22863164): 16 adults with untreated hypertension, single sessions in crossover A trial design in which each participant receives both the treatment and the comparison, one after the other, and serves as their own control.; exercise followed by sauna lowered 24-hour systolic pressure. Against them, Debray et al. (J Appl Physiol, 2023; PMID 37650138): 41 adults with coronary disease, 8 weeks of sauna alone, four sessions a week; blood pressure did not change. One small positive trial of sauna added to exercise, not repeated by an independent group, and one trial of sauna alone that found nothing: C.
As studied, and the trials
Debray et al. (J Appl Physiol, 2023; PMID 37650138): 41 adults with stable coronary disease randomized to 8 weeks of Finnish sauna (79 degrees Celsius, 20 to 30 minutes, four times a week) or no change. Resting core temperature fell and sweating rose, so the body adapted to the heat, but flow-mediated dilation, arterial stiffness and blood pressure did not differ from control. A single session in a similar population raised flow-mediated dilation for about an hour (Gravel et al., 2021, listed below under why the claim persists), which is why the acute finding and the 8-week finding are shown apart. Tested, no benefit.
As studied, and the trials
Lee et al. (Physiol Rep, 2025; PMID 40611569): 38 sedentary adults randomized to exercise plus 15 minutes of sauna, exercise alone or control for 8 weeks. Exercise improved heart rate variability; adding sauna gave no further change on any measure. Tested, no benefit.
As studied, and the trials
Kanji et al. (J Altern Complement Med, 2015; PMID 25636135): 37 adults with chronic tension-type headache randomized to advice plus regular sauna or advice alone for 8 weeks. Headache intensity fell by 1.27 points more on a 10-point scale with sauna (95% CI 0.48 to 2.07). Headache duration, sleep, depression scores and headache disability did not differ. One small unblinded trial on a self-reported endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score.: C.
As studied, and the trials
Pach et al. (Med J Aust, 2010; PMID 21143077): 157 adults with a new cold sat in a hot sauna in winter coats and breathed either hot dry air or room-temperature air for 3 days. Overall symptom severity did not differ (difference -3.9, 95% CI -9.7 to 1.9). Day 2 symptoms, day 1 medication use and self-rated effectiveness favored hot air. The primary endpoint The one outcome a trial names in advance as its main test. Results on other outcomes carry less weight. was null. Tested, no benefit.
Read the grade that matches your goal. How EBL grades by use →
A letter describes the human evidence, not the product, the manufacturer, or the intervention's worth.
See the full evidence record →Graded on Blood pressure and cardiorespiratory fitness when sauna follows exercise; headache pain (self-report).
Each use, with its trials
This record carries a separate letter for each thing it has been measured on. The headline grade is the best of them, and it does not transfer to the others.
Lee et al. (Am J Physiol Regul Integr Comp Physiol, 2022; PMID 35785965): 47 sedentary adults with a cardiovascular risk factor, randomized to exercise plus 15 minutes of sauna, exercise alone or no change for 8 weeks; adding sauna lowered systolic pressure by 8 mmHg more than exercise alone (95% CI -14.6 to -1.4) and raised VO2max by 2.7 mL/kg/min more. Gayda et al. (J Clin Hypertens, 2012; PMID 22863164): 16 adults with untreated hypertension, single sessions in crossover; exercise followed by sauna lowered 24-hour systolic pressure. Against them, Debray et al. (J Appl Physiol, 2023; PMID 37650138): 41 adults with coronary disease, 8 weeks of sauna alone, four sessions a week; blood pressure did not change. One small positive trial of sauna added to exercise, not repeated by an independent group, and one trial of sauna alone that found nothing: C.
Debray et al. (J Appl Physiol, 2023; PMID 37650138): 41 adults with stable coronary disease randomized to 8 weeks of Finnish sauna (79 degrees Celsius, 20 to 30 minutes, four times a week) or no change. Resting core temperature fell and sweating rose, so the body adapted to the heat, but flow-mediated dilation, arterial stiffness and blood pressure did not differ from control. A single session in a similar population raised flow-mediated dilation for about an hour (Gravel et al., 2021, listed below under why the claim persists), which is why the acute finding and the 8-week finding are shown apart. Tested, no benefit.
Lee et al. (Physiol Rep, 2025; PMID 40611569): 38 sedentary adults randomized to exercise plus 15 minutes of sauna, exercise alone or control for 8 weeks. Exercise improved heart rate variability; adding sauna gave no further change on any measure. Tested, no benefit.
Kanji et al. (J Altern Complement Med, 2015; PMID 25636135): 37 adults with chronic tension-type headache randomized to advice plus regular sauna or advice alone for 8 weeks. Headache intensity fell by 1.27 points more on a 10-point scale with sauna (95% CI 0.48 to 2.07). Headache duration, sleep, depression scores and headache disability did not differ. One small unblinded trial on a self-reported endpoint: C.
Pach et al. (Med J Aust, 2010; PMID 21143077): 157 adults with a new cold sat in a hot sauna in winter coats and breathed either hot dry air or room-temperature air for 3 days. Overall symptom severity did not differ (difference -3.9, 95% CI -9.7 to 1.9). Day 2 symptoms, day 1 medication use and self-rated effectiveness favored hot air. The primary endpoint was null. Tested, no benefit.
Why this letter
Why this gradeGrade C, small or unreplicated trials. The reasoning, and what the grade does not cover.
Grade C. The randomized evidence on the traditional Finnish sauna is small and short. Sauna added after exercise lowered systolic pressure and raised fitness in one 47-person, 8-week trial (Lee et al., 2022; PMID 35785965), which has not been repeated by an independent group, and sauna alone changed neither vascular function nor blood pressure in 41 people with coronary disease over the same 8 weeks (Debray et al., 2023; PMID 37650138). Blood pressure is an established stand-in for heart disease, but one positive trial against one null trial does not meet the B definition. Headache pain fell in one 37-person unblinded trial (Kanji et al., 2015; PMID 25636135), a self-reported endpoint from a single trial.
WHAT THIS GRADE DOES NOT COVERmortality, dementia and stroke. The Kuopio cohort findings (PMID 25705824; PMID 27932366; PMID 29720543) are observational Research that watches what people already do rather than assigning a treatment. It can show that two things travel together, not that one causes the other., and no randomized trial has tested sauna against any of those outcomes. Infrared saunas and the Japanese Waon protocol are a different exposure and are graded on their own record.
A grade describes the human evidence for a named use. It is not advice, and it is not a judgment on any individual prescription. How the letters are decided →
Evidence notes: randomized trial
Endpoint graded: Blood pressure and cardiorespiratory fitness when sauna follows exercise; headache pain (self-report) (surrogate)
Last reviewed: October 2026
The trial that would change this grade.
A positive trial of this shape, supported by further trials, would move this entry to B.
Why the current trials fall short
The positive blood pressure trial was 47 people for 8 weeks and has not been repeated. A larger, longer trial from an independent group, separating sauna from exercise, is what is missing.
Why people believe itThree human sources; no published case reports of benefit; three reports of harm.
The case for the Finnish sauna is that heat makes the heart beat faster and the blood vessels widen, a little like moderate exercise, and that doing this several times a week trains the circulation. The Kuopio cohort in eastern Finland, where most homes have a sauna, found that men who used one most often lived longer and had less heart disease and dementia, and those papers are behind most of what is said about sauna today.
What supporters point to, and what each source actually shows. None of it is enough to move this letter higher; the trial described above under Evidence wanted is what would.
- Population study, not a trialIn 2,315 Finnish men followed for about 20 years, those taking a sauna 4 to 7 times a week had fewer sudden cardiac deaths and fewer deaths from any cause than those taking one a week. An association, not a trial. PMID 25705824
- Population study, not a trialIn the same men, 4 to 7 sessions a week was associated with about a third of the dementia risk of one a week. An association, not a trial. PMID 27932366
- Human trial, blood or body markerIn 22 adults with coronary disease, one Finnish sauna session raised flow-mediated dilation for about an hour and lowered blood pressure. A single session with no control group; an 8-week randomized trial in the same population found no lasting change (PMID 37650138). PMID 32615263
A case report describes what happened to one or a few patients. It cannot show the treatment caused the change, and reports of success are published more often than reports of failure.
A PubMed search in October 2026 found no published case report of benefit for this use.
- A patient had a heart attack, thought to come from coronary artery spasm, after alternating between a hot sauna and rapid cooling in cold water. PMID 10085493
- A 44-year-old man with keratoconus developed sudden swelling of both corneas, three years apart, each time the evening after a hot, humid Finnish sauna; both eyes needed corneal transplants. PMID 2763821
- A 70-year-old woman who fell asleep for 30 minutes in a Korean-style hot dry sauna with a wet towel over her thigh sustained a second-degree burn under the towel. PMID 23348336
Searched PubMed, October 2026: 81 case report record(s) returned. Most describe harm: burns, deaths with alcohol or drugs, heat stroke, muscle breakdown and drug-patch overdoses; three are listed that involve a traditional sauna. Reports of benefit are mostly far-infrared or Waon therapy and are listed on the infrared sauna record. The rest concern sauna-acquired infections, skin conditions and unrelated uses of the word.
Dose, form and timing
Resting blood pressure and heart rate at baseline and after 8 weeks, the interval the trials used. Session temperature, humidity, minutes per session and sessions per week, so the routine can be set against the studied protocols (about 79 to 81 degrees Celsius, 13 to 23 percent humidity, 15 to 30 minutes, three or four times a week). Fluids taken in and body weight before and after a session.
As studiedDose, form, population and duration for every use.
Home and gym saunas sold as traditional or Finnish vary in temperature, humidity and how much water is thrown on the stones. The observational Kuopio findings come from Finnish men using their own saunas, mostly 2 to 7 times a week; an infrared cabin is a different exposure and is graded separately.
A grade describes the intervention that was tested. Where the product on the shelf differs from it, this says so.
Safety
Deaths in saunas are rare, and alcohol is the common thread. In Finland, from 1990 to 2002, deaths occurring in a sauna ran at fewer than 2 per 100,000 people a year, and half of those who died were under the influence of alcohol (PMID 18471223). In Sweden, 71 percent of those tested had alcohol in the blood, and all but two were found alone (PMID 19749613). In 10 men who used a Finnish sauna twice a week for 3 months, sperm count and motility fell sharply and recovered within 6 months of stopping (PMID 23411620). In a cohort of 23,491 pregnant women, hot tub use in early pregnancy was linked with neural tube defects; the estimate for sauna pointed the same way but was not statistically significant Unlikely to be explained by chance alone at the threshold the study set. It says nothing about whether the difference is large enough to matter. (PMID 1640616). In people taking insulin, a sauna roughly doubled the rate at which injected insulin was absorbed and lowered blood glucose (PMID 7000239).
Grade history
How this letter has changedLatest: October 2026 · First graded.
The traditional Finnish sauna now has its own record, separate from infrared saunas. Sauna added after exercise lowered systolic blood pressure by 8 mmHg more than exercise alone in 47 adults over 8 weeks (Lee et al., Am J Physiol Regul Integr Comp Physiol, 2022; PMID 35785965), and sauna alone changed neither vascular function nor blood pressure in 41 adults with coronary disease (Debray et al., J Appl Physiol, 2023; PMID 37650138): Grade C. The Kuopio cohort findings on mortality, dementia and stroke (Laukkanen et al., JAMA Intern Med, 2015; PMID 25705824) are shown on the record as observational and carry no letter.PMID 35785965 PMID 37650138 PMID 25705824
Every change to a letter on this site is dated and published. The full evidence log →
Sources
The evidence, in fullSix papers, each linked to its PubMed record.
Lee et al. (Am J Physiol Regul Integr Comp Physiol, 2022; PMID 35785965): 47 adults, sauna after exercise for 8 weeks lowered systolic pressure and raised fitness more than exercise alone. Debray et al. (J Appl Physiol, 2023; PMID 37650138): 41 adults with coronary disease, 8 weeks of sauna, no change in vascular function or blood pressure. Lee et al. (Physiol Rep, 2025; PMID 40611569): sauna after exercise added nothing to heart rate variability. Kanji et al. (J Altern Complement Med, 2015; PMID 25636135): 37 adults, less tension-type headache pain. Pach et al. (Med J Aust, 2010; PMID 21143077): 157 adults, breathing hot sauna air did not ease a cold. Gayda et al. (J Clin Hypertens, 2012; PMID 22863164): in single sessions, exercise followed by sauna lowered 24-hour blood pressure in untreated hypertension. Grade C: small, short trials on blood pressure, fitness and self-reported pain, with null results beside them.
Primary evidenceSix papers, each linked to its PubMed record.
Lee et al. (Am J Physiol Regul Integr Comp Physiol, 2022; PMID 35785965): 47 adults, sauna after exercise for 8 weeks lowered systolic pressure and raised fitness more than exercise alone. Debray et al. (J Appl Physiol, 2023; PMID 37650138): 41 adults with coronary disease, 8 weeks of sauna, no change in vascular function or blood pressure. Lee et al. (Physiol Rep, 2025; PMID 40611569): sauna after exercise added nothing to heart rate variability. Kanji et al. (J Altern Complement Med, 2015; PMID 25636135): 37 adults, less tension-type headache pain. Pach et al. (Med J Aust, 2010; PMID 21143077): 157 adults, breathing hot sauna air did not ease a cold. Gayda et al. (J Clin Hypertens, 2012; PMID 22863164): in single sessions, exercise followed by sauna lowered 24-hour blood pressure in untreated hypertension. Grade C: small, short trials on blood pressure, fitness and self-reported pain, with null results beside them.
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How EBL searched for the trials (1 search)
The search that was run, what it returned, and what was left out and why, so the absence of evidence can be checked as well as its presence.
("Finnish sauna"[tiab] OR "sauna bathing"[tiab] OR "dry sauna"[tiab] OR "traditional sauna"[tiab]) AND randomized controlled trial[pt]Disclosure
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