Sauna for essential (primary) hypertension
Evidence review
Overview
In the Kuopio Ischaemic Heart Disease (KIHD) cohort, men who used a sauna 4-7 times per week had a lower risk of developing hypertension than men who used it once weekly; this is an association in initially normotensive men. Single sauna or hot-water immersion sessions acutely lower blood pressure in hypertensive patients (including central pressure after an ordinary home bath, without a difference in night-time pressure), but in a randomized crossover trial a single 185-194 F sauna session alone did not lower 24-hour ambulatory pressure; only exercise followed by sauna did. Older uncontrolled and non-randomized German studies reported lower resting pressure after months of regular sauna. Controlled evidence for a sustained effect is limited: an 8-week RCT found lower systolic pressure when sauna was added to exercise in adults with cardiovascular risk factors, while an 8-week sham-controlled RCT of home lower-leg hot-water immersion in hypertensive women found no change in ambulatory pressure. Meta-analyses of heat-therapy trials report modest systolic reductions (about 2-4 mmHg), but the most recent RCT-only meta-analysis found no significant overall effect on systolic or diastolic pressure.
Key findings
- KIHD cohort (n=1,621 normotensive men, 24.7-year median follow-up): incident hypertension HR 0.53 (95% CI 0.28-0.98) for 4-7 vs 1 session/week after full adjustment.
- 8-week RCT (n=47, sedentary adults with >=1 CVD risk factor): exercise plus 15-min sauna lowered systolic BP by 8.0 mmHg (95% CI -14.6 to -1.4) vs exercise alone.
- Sham-controlled RCT in hypertensive postmenopausal women (n=59, 8 weeks of home lower-leg immersion at 107.6 F): larger acute falls per session, but no difference in ambulatory BP change (awake systolic +2 vs 0 mmHg; 24-h, awake and asleep all P>=0.13).
- Randomized crossover in treated hypertension (n=16): 24-h systolic BP 7 mmHg lower (95% CI -11 to -2) after one 40-min immersion at 104 F vs no immersion, but thermoneutral immersion lowered it similarly (-6 mmHg).
- Randomized crossover in untreated prehypertension or stage I hypertension (n=16): 24-h systolic BP 134 mmHg after sauna alone vs 136 mmHg after control (no effect) and 131 mmHg after exercise plus sauna (P=.04).
- RCT meta-analysis (20 trials, 2025): overall SBP change -2.46 mmHg (95% CI -5.02 to 0.10) and DBP -1.08 mmHg (95% CI -2.79 to 0.63), both not significant; whole-body heating subgroup SBP -4.11 mmHg (95% CI -7.36 to -0.86).
- Heat-therapy meta-analysis (15 studies, 2021): SBP -3.94 mmHg (95% CI -7.22 to -0.67), DBP -3.88 mmHg (95% CI -6.13 to -1.63).
- Uncontrolled 3-month study in hypertensive men (n=46): resting and dynamic-exercise BP fell significantly; BP during isometric exercise did not.
- A single sauna session in untreated hypertension shifted heart rate variability toward sympathetic predominance, normalizing within 15-120 min (n=10).
- Home hot-water bath (105.1 F) in treated hypertension (n=28): central systolic BP fell 13.0 mmHg and brachial BP 8.0/8.3 mmHg after bathing, but night-time BP did not differ between bathing and non-bathing days (Ishikawa 2016).
Every study we reviewed
7 found benefit · 8 mixed results · 2 found no effect
Each study was checked on PubMed. The colored edge shows the direction of the result. The research library lists 44 studies on hypertension, across all heat and cold therapies, including case reports and older work not graded here.
The effect of heat therapy on blood pressure and peripheral vascular function: A systematic review and meta-analysis.
Pizzey FK et al. Exp Physiol. 2021. PubMed 33866630 · DOI · Free full text
- Who
- 15 studies of heat therapy (sauna, hot water immersion and other modes) in healthy and clinical populations
- What
- Repeated heat therapy, 30-90 min exposures over 10-36 sessions, vs control
- Measured
- Resting BP, flow-mediated dilation
- Result
- SBP MD -3.94 mmHg (95% CI -7.22 to -0.67; 10 studies); DBP MD -3.88 mmHg (95% CI -6.13 to -1.63; 9 studies); MAP MD -5.86 mmHg (95% CI -8.63 to -3.10); GRADE certainty moderate for SBP/DBP.
- Limitations
- Pooled heterogeneous heating modes and populations; not limited to RCTs in hypertensive patients.
Non-acute effects of passive heating interventions on cardiometabolic risk and vascular health: systematic review and meta-analysis of randomized controlled trials.
Hamaya R et al. Am J Prev Cardiol. 2025. PubMed 41049507 · DOI · Free full text
- Who
- 20 RCTs of passive heating >=1 week (hot water bathing, sauna, hot yoga, local heating) in adults
- What
- Passive heating interventions, 2-15 weeks
- Protocol
- 2-15
- Measured
- Systolic BP and other cardiometabolic markers
- Result
- Overall SBP -2.46 mmHg (95% CI -5.02 to 0.10; 15 RCTs; I2 60.3%), not significant; DBP -1.08 mmHg (95% CI -2.79 to 0.63; 13 RCTs), not significant; whole-body heating subgroup SBP -4.11 mmHg (-7.36 to -0.86); coronary risk/CVD subgroup -2.52 mmHg (-4.26 to -0.79; between-subgroup heterogeneity p=0.058).
- Limitations
- High heterogeneity; subgroup findings; mixed modalities; most included trials at moderate to high risk of bias (unblinded, small, not pre-registered); funnel asymmetry suggests small-study effects; adverse events not pooled.
Effects of regular sauna bathing in conjunction with exercise on cardiovascular function: a multi-arm, randomized controlled trial.
Lee E et al. Am J Physiol Regul Integr Comp Physiol. 2022. PubMed 35785965 · DOI · Free full text
- Who
- Sedentary adults (mean age 49) with >=1 CVD risk factor; 35% had elevated BP at entry
- What
- Guideline exercise + 15-min post-exercise Finnish sauna (EXS) vs exercise alone (EXE) vs control, 8 weeks
- Protocol
- 149 rising to about 176 °F · 15 min · 3/wk · 8 wk
- Measured
- Systolic BP, cardiorespiratory fitness
- Result
- Systolic BP -8.0 mmHg (95% CI -14.6 to -1.4) for EXS vs EXE; CRF +2.7 mL/kg/min (95% CI 0.2-5.3) for EXS vs EXE.
- Limitations
- Small (48 randomized, 47 analysed; 42 of 48 women); sauna always combined with exercise; most participants not hypertensive; open-label with only the statistician blinded; no follow-up after 8 weeks.
Home-based lower leg heat therapy in postmenopausal women with hypertension. I. Effects on blood pressure.
Akins JD et al. J Appl Physiol (1985). 2026. PubMed 42804377 · DOI · Free full text
- Who
- Postmenopausal women with treated or untreated hypertension, mean age 69 (USA)
- What
- Home-based lower-leg hot-water immersion at 107.6 F (n=29) vs thermoneutral sham immersion at 95 F (n=30)
- Protocol
- 107.6 (sham 95) °F · 45 min · about 4/wk · 8 wk
- Measured
- 24-h ambulatory BP (pre to post intervention); acute BP response to each immersion
- Result
- Acute falls per session were larger with heat (SBP -6 vs -2 mmHg, DBP -5 vs -2 mmHg; P<0.01), but change in awake ambulatory BP (the prespecified chronic outcome) did not differ between groups (systolic +2 +/- 8 heat vs 0 +/- 8 mmHg sham; P=0.38), and 24-h, awake and asleep BP showed no group difference (all P>=0.13). Four participants reported non-serious adverse events during sessions (profuse sweating 2, lower-leg reddening resolving within 36 h 1, hip discomfort 1; group not stated).
- Limitations
- Lower-leg heating only; women only; home-based sessions with adherence not directly verified; one participant excluded for poor BP data; results may not apply to whole-body sauna.
Effects of sauna alone and postexercise sauna baths on blood pressure and hemodynamic variables in patients with untreated hypertension.
Gayda M et al. J Clin Hypertens (Greenwich). 2012. PubMed 22863164 · DOI · Free full text
- Who
- 16 untreated adults aged 33-71 (13 men): 8 prehypertensive (SBP 120-139 mmHg) and 8 stage I hypertensive (SBP 140-159 mmHg) (Canada)
- What
- Single sessions in random crossover order, at least 3 days apart: resting control vs sauna alone vs 30-min cycling at 75% of maximal heart rate followed by sauna
- Protocol
- 185-194 °F · 16 (2 x 8) min · single session/wk
- Measured
- 24-h ambulatory BP, total vascular resistance
- Result
- 24-h systolic BP 136 +/- 11 (control), 134 +/- 9 (sauna alone) and 131 +/- 12 mmHg (exercise plus sauna; lower than control and sauna alone, P=.04). Sauna alone had no effect on 24-h ambulatory BP or on BP 15 and 120 min later; both sauna conditions lowered total vascular resistance at 15 and 120 min (P<.01). All patients completed both sauna periods; one transient systolic BP drop occurred at the second minute of the first sauna period.
- Limitations
- Acute single sessions; small; half the participants were prehypertensive rather than hypertensive; unblinded, randomization method not stated; the 24-h BP reduction appeared only when sauna followed exercise.
Effects of sauna alone versus postexercise sauna baths on short-term heart rate variability in patients with untreated hypertension.
Gayda M et al. J Cardiopulm Rehabil Prev. 2012. PubMed 22561416 · DOI
- Who
- Adults with untreated hypertension, mean age 59 (Canada)
- What
- Single sessions randomized: control rest vs two 8-min sauna sessions vs 30-min aerobic exercise followed by sauna
- Protocol
- 16 (2 x 8) min · single session/wk
- Measured
- Short-term heart rate variability
- Result
- During sauna, LF (normalized units) and LF/HF rose (P<.05 and P<.01) and HF fell (P<.05), indicating increased sympathetic and reduced parasympathetic drive; changes normalized within 15-120 min after sauna.
- Limitations
- Very small; acute single session; HRV is a surrogate.
[Use of walking and sauna therapy in the rehabilitation of hypertensive patients with ischemic heart disease following aortocoronary venous bypass operation with special reference to hemodynamics].
Winterfeld HJ et al. Z Kardiol. 1988. PubMed 3260059
- Who
- Untrained hypertensive men with ischemic heart disease after coronary artery bypass grafting (East Germany)
- What
- Rehabilitation with Finnish sauna vs walking/running training
- Measured
- BP at rest and on exercise (also LVEF and peripheral microcirculation)
- Result
- Blood pressure at rest and during exercise was not influenced by sauna or walking rehabilitation; resting LVEF rose by about 7-8% in both groups and peripheral microcirculation improved only with sauna.
- Limitations
- German-language report, abstract only; no untreated control, so the LVEF rise cannot be attributed to sauna; randomization details and numeric results limited.
Both hot- and thermoneutral-water immersion reduce 24-h blood pressure in people with hypertension: A randomized crossover study.
Roxburgh BH et al. Temperature (Austin). 2025. PubMed 40330610 · DOI · Free full text
- Who
- Adults with hypertension taking at least one antihypertensive, mean age 62, 11 women (New Zealand)
- What
- Single sessions in random order: 20-min and 40-min hot-water immersion at 104 F, 40-min thermoneutral immersion at 97.7 F, seated control
- Protocol
- 104 (thermoneutral 97.7) °F · 20 or 40 min · single session each/wk
- Measured
- 24-h ambulatory BP after each session
- Result
- 24-h SBP vs control: -7 mmHg (95% CI -11 to -2) after 40-min hot immersion, -6 (-10 to -1) after 20-min hot immersion, and -6 (-9 to -3) after thermoneutral immersion; 24-h DBP not different (p=0.093). No adverse events; one participant withdrew after two exposures.
- Limitations
- Single-session effects only; thermoneutral immersion lowered BP similarly, so the effect was not specific to heat; small; unblinded.
[Effect of sauna and walking series on blood pressure, peripheral microcirculation and performance behavior in essential hypertension].
Winterfeld HJ et al. Z Gesamte Inn Med. 1983. PubMed 6649721
- Who
- Stage I-II essential hypertension pretreated with propranolol (East Germany)
- What
- Series of sauna baths vs series of running, lasting several weeks
- Protocol
- several
- Measured
- BP at rest and under load, peripheral microcirculation (xenon-133 muscle clearance)
- Result
- Both sauna and running series produced significant reductions in resting BP and improved peripheral hemodynamics; BP at higher exercise loads was not influenced.
- Limitations
- Sample size, allocation method and numeric results not given in abstract; German-language report.
[Potential use of the sauna in the long-term treatment of hypertensive cardiovascular circulation disorders--a comparison with kinesiotherapy].
Winterfeld HJ et al. Schweiz Rundsch Med Prax. 1992. PubMed 1410979
- Who
- Patients with essential hypertension, coronary heart disease with hypertension, or after coronary bypass surgery (East Germany)
- What
- Finnish sauna twice weekly (n=65) vs regular kinesiotherapy (running and swimming, n=68), followed 1 and 3 years
- Protocol
- 2/wk · 52-156
- Measured
- BP and heart rate at rest and at 50 W, peripheral microcirculation, LVEF, cardiac output
- Result
- Regular sauna had a positive effect on BP regulation and hemodynamics in hypertension and in coronary disease with hypertension, as did kinesiotherapy. No numeric results in abstract.
- Limitations
- Non-randomized comparison with exercise; mixed diagnoses; no numbers in abstract; German-language report.
Sauna Bathing and Incident Hypertension: A Prospective Cohort Study.
Zaccardi F et al. Am J Hypertens. 2017. PubMed 28633297 · DOI · Free full text
- Who
- Middle-aged Finnish men (42-60 y) without hypertension at baseline (KIHD)
- What
- Self-reported Finnish sauna frequency: 2-3 or 4-7 vs 1 session/week
- Protocol
- 1 vs 2-3 vs 4-7/wk
- Measured
- Incident hypertension (diagnosis, SBP >140, DBP >90 or antihypertensive use)
- Result
- HR 0.54 (95% CI 0.32-0.91) for 4-7 vs 1 session/week adjusted for age, smoking, BMI, SBP; HR 0.53 (0.28-0.98) after further adjustment incl. cardiorespiratory fitness and SES; 2-3 sessions/week HR 0.83 (0.59-1.18). 251 incident cases.
- Limitations
- Observational association; men only; sauna habits self-reported once at baseline; residual confounding possible; prevention in normotensive men, not treatment of established hypertension.
The Interplay between Systolic Blood Pressure, Sauna Bathing, and Cardiovascular Mortality in Middle-Aged and Older Finnish Men: A Cohort Study.
Laukkanen JA et al. J Nutr Health Aging. 2023. PubMed 37248758 · DOI · Free full text
- Who
- Finnish men aged 42-61 (KIHD)
- What
- Sauna frequency high (3-7/week) vs low (<=2/week), cross-classified with SBP
- Protocol
- <=2 vs 3-7/wk
- Measured
- CVD mortality
- Result
- Low vs high sauna frequency HR 1.24 (95% CI 1.03-1.51). Versus normal SBP + high frequency: high SBP (>=140) + low frequency HR 1.81 (1.39-2.36); high SBP + high frequency HR 1.52 (1.06-2.16). With a 130 mmHg cut-off, high SBP + high frequency HR 1.11 (0.77-1.61).
- Limitations
- Observational; men only; formal interaction tests between sauna frequency and SBP were not significant (RERI 0.02, 95% CI -0.51 to 0.55), so the authors' suggestion that frequent sauna may offset risk for high-normal SBP rests on a subsidiary 130 mmHg analysis; no benefit seen for SBP >=140 mmHg.
Sauna bathing and mortality risk: unraveling the interaction with systolic blood pressure in a cohort of Finnish men.
Kunutsor SK et al. Scand Cardiovasc J. 2024. PubMed 38410962 · DOI · Free full text
- Who
- Finnish men aged 42-61 (KIHD)
- What
- Sauna frequency high (3-7/week) vs low (<=2/week), cross-classified with SBP
- Protocol
- <=2 vs 3-7/wk
- Measured
- All-cause mortality
- Result
- High SBP + low frequency HR 1.47 (95% CI 1.24-1.74) vs normal SBP + high frequency; high SBP + high frequency HR 1.24 (0.98-1.57).
- Limitations
- Observational; same cohort as other KIHD analyses; men only.
Blood pressure-lowering effect of repeated Waon therapy in non-smokers with hypertension.
Kominami K et al. Medicine (Baltimore). 2021. PubMed 34115020 · DOI · Free full text
- Who
- Patients with hypertension on standard therapy (mean age 64, 17 of 31 men) given Waon therapy at one Japanese center
- What
- Waon therapy once daily; repeated-session analysis in 22 of 31 patients who had at least 5 sessions (mean 10.3, range 5-25)
- Protocol
- 140 °F · 15 min · daily/wk
- Measured
- Seated BP before vs after sessions
- Result
- Single session: SBP 118.5 to 115.1 mmHg, DBP 70.5 to 65.9 mmHg (both P<.001). Repeated sessions, all patients: SBP 122.3 to 116.9 mmHg (not significant). Non-smokers (n=11): SBP 124.2 to 108.8 mmHg, DBP 73.6 to 62.1 mmHg (P<.001).
- Limitations
- Retrospective and uncontrolled; small smoker/non-smoker subgroups (11 each) that differed in age, weight and medication use; baseline BP already controlled; overall repeated-session effect not significant; no follow-up after the course. No adverse events such as hypotension or falls were reported.
Acute effects of sauna bathing on cardiovascular function.
Laukkanen T et al. J Hum Hypertens. 2018. PubMed 29269746 · DOI · Free full text
- Who
- Adults (mean age 52) with >=1 cardiovascular risk factor
- What
- Single Finnish sauna session
- Protocol
- 163 °F · 30 min · single session/wk
- Measured
- BP and carotid-femoral pulse wave velocity immediately after sauna
- Result
- SBP 137 to 130 mmHg, DBP 82 to 75 mmHg (both p<0.0001); PWV 9.8 to 8.6 m/s (p<0.0001). SBP remained lower after 30-min recovery.
- Limitations
- Single-arm acute study without a control condition; does not show a sustained effect.
[The behavior of central and peripheral hemodynamics in isometric and dynamic stress in hypertensive patients treatment with regular sauna therapy].
Siewert C et al. Z Kardiol. 1994. PubMed 7801668
- Who
- Hypertensive men, WHO stage I-II, mean age 41 (East Germany)
- What
- Regular sauna therapy for 3 months (no control group)
- Protocol
- about 13
- Measured
- BP at rest, during dynamic and isometric exercise; cardiac output; muscle clearance
- Result
- Systolic and diastolic BP at rest and during dynamic exercise fell significantly (p<=0.01); BP during isometric exercise did not change (157.5 to 155.0 mmHg); cardiac output and total peripheral resistance unchanged; muscle clearance half-time 4.4 to 3.2 min (p<=0.01).
- Limitations
- Uncontrolled; German-language report, abstract only; resting BP values not given in abstract.
Reduction in central blood pressure after bathing in hot water.
Ishikawa J et al. Blood Press Monit. 2016. PubMed 26657048 · DOI
- Who
- Treated Japanese hypertensive patients, mean age 65.5 (46% men)
- What
- Habitual home hot-water bath, mean water temperature 105.1 F (40.6 C), with 24-h ambulatory central BP monitoring on bathing and non-bathing days
- Protocol
- 105.1 °F
- Measured
- Central and brachial BP after bathing; night-time BP on bathing vs non-bathing days
- Result
- Central systolic BP fell 13.0 mmHg after bathing (140.7 to 127.7 mmHg, P=0.019, n=20); brachial BP fell 8.0/8.3 mmHg (P=0.023 and P<0.001). Night-time brachial and central BP did not differ between bathing and non-bathing days.
- Limitations
- Acute within-person comparison of habitual bathing; patients removed and reattached monitors themselves; no randomization.
Protocols used in the studies
Cohort data reflect habitual Finnish sauna use (temperature not recorded in abstracts), with the strongest association at 4-7 sessions/week. The RCT used 15-min Finnish sauna after exercise 3 times/week for 8 weeks, starting at 149 F (65 C) and rising about 9 F (5 C) every two weeks. Waon studies used a 140 F (60 C) far-infrared sauna for 15 min plus 30 min blanket rest, once daily. Acute studies used a single 30-min session at 163 F (73 C) or two 8-min sessions at 185-194 F (85-90 C) separated by a cold shower and 10 min rest. Hot-water immersion studies used 104 F (40 C) for 20-40 min (single sessions) or home lower-leg immersion at 107.6 F (42 C) for 45 min about 4 times/week for 8 weeks. Older German studies used regular Finnish sauna about twice weekly for 3 months to 3 years (temperatures not given in abstracts).
What is still unknown
No adequately powered, sham- or time-controlled RCT of sauna alone with 24-hour ambulatory BP in diagnosed hypertension; whether acute post-immersion falls reflect heat or water immersion itself; optimal temperature, duration and frequency; durability after stopping; effects in women and non-Finnish populations.
Safety
Cautions for sauna in this condition
- Sauna produces acute falls in systolic and diastolic BP (e.g. -7 mmHg in both after 30 min at 163 F; PMID 29269746); patients on antihypertensives, especially vasodilators or diuretics, may be prone to orthostatic symptoms on standing.
- A single sauna session acutely shifts autonomic balance toward sympathetic predominance in untreated hypertension, normalizing within about 2 hours (PMID 22561416).
- In the KIHD analysis, frequent sauna use did not offset the excess CVD mortality associated with SBP >=140 mmHg (PMID 37248758); sauna is not a substitute for guideline antihypertensive treatment.
- Alcohol was present in about half of sauna deaths in a Finnish forensic series (PMID 18471223); avoid alcohol before and during sauna.
For clinicians
Suggested rationale
Regular sauna use was associated with a lower incidence of hypertension in a 25-year prospective cohort (Zaccardi 2017, HR 0.53 for 4-7 vs 1 session/week), and a small RCT found an additional 8 mmHg systolic reduction when sauna was added to exercise (Lee 2022), but a single sauna session alone did not lower 24-hour BP in untreated hypertension (Gayda 2012) and a sham-controlled trial of home lower-leg hot-water immersion found no sustained ambulatory BP reduction (Akins 2026); sauna may be considered an adjunct to, not a replacement for, standard antihypertensive therapy.
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