Evidence ReviewEvidence: Moderate

Infrared Sauna and Blood Pressure: The Research, Explained

Blood pressure is one of the better-studied effects of heat therapy. A single sauna session reliably lowers blood pressure for an hour or so afterward, and decades of Finnish cohort data tie frequent sauna use to a lower risk of ever developing hypertension. Most of the strongest numbers come from traditional sauna, but the mechanism (heat-driven vasodilation and improved endothelial function) is shared by infrared. Here is what the research actually shows, how large the effect is, and who needs to be careful.

Key Takeaways

01Acute effect: a single 30-minute sauna dropped systolic BP from 137 to 130 mmHg and diastolic from 82 to 75 mmHg in a 2018 study of 102 at-risk adults (Laukkanen group).
02Chronic effect: in the Finnish KIHD cohort, men using a sauna 4-7 times per week had about a 46% lower risk of developing hypertension versus once-weekly users.
03Mechanism: heat causes peripheral vasodilation and, with regular use, improved endothelial function and reduced arterial stiffness.
04Waon therapy, a 60 C far-infrared protocol developed in Japan, improved endothelial function (flow-mediated dilation 3.6% to 5.1%) and outcomes in chronic heart failure patients.
05Caution: BP rises during the heat phase, the post-session drop can cause orthostatic hypotension, and several BP medications amplify that drop.

-7 mmHg

Acute systolic drop

After one 30-min session (137 to 130), 2018 J Human Hypertension, n=102

46%

Lower hypertension risk

Sauna 4-7x/week vs 1x/week, KIHD cohort, 2,315 Finnish men

3.6 to 5.1%

Endothelial function (FMD)

Waon far-infrared therapy in chronic heart failure patients

The Mechanism: Why Heat Lowers Blood Pressure

The blood pressure effect of sauna is not mysterious. It follows directly from how the body sheds heat. When you sit in a hot cabin, your core temperature begins to rise, and the body responds by sending more blood to the skin so it can radiate heat away. To do that, the small blood vessels near the surface widen. This widening is called vasodilation, and it is the single most important reason blood pressure behaves the way it does around a sauna session.

Vasodilation lowers the resistance the heart pumps against. When the vessels relax and open, there is more room in the system, so the pressure inside it falls. That is the acute effect: in the hour after a session, with vessels still dilated, measured blood pressure tends to sit below baseline. There is a complication worth being honest about, which is that blood pressure usually rises slightly during the hot phase itself, because heart rate climbs to move blood faster. The net favorable effect shows up afterward, in the recovery window, not in the middle of the heat.

Endothelial Function: The Long-Term Pathway

Repeated heat exposure appears to do something more durable than a temporary dip. The endothelium is the thin layer of cells lining your blood vessels, and its health largely determines how well vessels dilate on demand. Regular sauna use is associated with improved endothelial function and reduced arterial stiffness, both of which support lower resting blood pressure over time. The clearest demonstration comes from Waon therapy, a far-infrared protocol described in the next section, which measured flow-mediated dilation (a standard test of endothelial function) improving from 3.6% to 5.1% in heart failure patients. Better endothelial function is the plausible bridge between a one-time session and the lower hypertension risk seen across years of regular use. For the broader cardiovascular picture, see our guide to infrared sauna and heart health.

The Evidence: What the Studies Found

The KIHD Cohort (Laukkanen): Hypertension Risk

The strongest long-term data comes from the Kuopio Ischemic Heart Disease (KIHD) study, a prospective cohort of 2,315 middle-aged Finnish men whose sauna habits were recorded at baseline and tracked for decades. In the hypertension analysis led by Jari Laukkanen and published in 2017, men who used a sauna 4 to 7 times per week had roughly a 46% lower risk of developing high blood pressure compared with men who went once a week. Those using it 2 to 3 times weekly saw about a 24% lower risk. The dose-response pattern, more sessions associated with lower risk, is part of what makes the finding credible.

Two honest caveats apply. First, this is observational data, so it shows association rather than proof of cause, and people who sauna frequently may differ in other ways. Second, the KIHD participants used traditional Finnish sauna, not infrared. The mechanism is shared, but the exact magnitude in an infrared cabin has not been measured at this scale.

The Acute Study: One Session, Measured

A 2018 study in the Journal of Human Hypertension, also from the Laukkanen group, looked at the immediate effect. It put 102 adults, each with at least one cardiovascular risk factor, through a single 30-minute session at 73 C. Mean systolic blood pressure fell from 137 to 130 mmHg and diastolic from 82 to 75 mmHg, both highly statistically significant. Systolic pressure remained below the pre-sauna level even 30 minutes after participants left the heat. The study also reported reduced arterial stiffness, which fits the vasodilation and endothelial story. This is the cleanest single number for the acute effect: about a 7 mmHg drop in each value.

Waon Therapy: Far-Infrared for the Heart

Waon therapy is the closest thing to infrared-specific evidence here. Developed by Dr. Chuwa Tei at Kagoshima University, it uses an evenly heated 60 C far-infrared dry sauna for 15 minutes followed by 30 minutes resting wrapped in blankets. In chronic heart failure patients, Waon therapy improved flow-mediated dilation from 3.6% to 5.1%, improved cardiac function markers, and lowered mean and diastolic arterial pressure at the end of recovery. The multicenter WAON-CHF trial linked the protocol to better long-term outcomes. These patients are sicker than the typical sauna user, but the results matter because they were produced with far-infrared heat and they confirm a real effect on the vasculature and blood pressure.

How Large Is the Effect, Really?

It helps to separate the two timescales, because they answer different questions and have different evidence behind them.

Timescale	Effect	Source	Evidence
Acute (one session)	Systolic -7, diastolic -7 mmHg	2018 J Human Hypertension, n=102	Moderate, traditional sauna
During heat phase	BP rises briefly	Cardiovascular physiology	Well established
Chronic (regular use)	~46% lower hypertension risk	KIHD cohort, 2,315 men	Moderate, observational
Far-infrared (clinical)	Endothelial + BP improvement	Waon therapy, CHF patients	Limited, sicker population

A useful way to read this: the acute 7 mmHg drop is real but it fades within an hour or two, so it is not a substitute for treatment of established hypertension. The long-term benefit, the lower risk of developing high blood pressure in the first place, seems to come from consistency rather than any single intense session. If you are using sauna with blood pressure in mind, frequency matters more than heat. Our piece on how often to use an infrared sauna covers sensible weekly targets.

Who Should Be Cautious

Heat therapy is favorable for blood pressure on balance, but the same vasodilation that helps can cause problems in specific situations. None of these is a reason for most people to avoid sauna, and each is a reason to be deliberate.

Orthostatic hypotension

After a session your vessels are dilated and your blood pressure is lower. Standing up quickly, especially from lying down, can drop pressure to the brain and cause lightheadedness or fainting. Stand slowly, sit on the bench before exiting, and avoid hot showers immediately after.

Blood pressure medications

Diuretics, beta blockers, and other vasodilators (including nitrates and many antihypertensives) amplify the post-sauna drop. Diuretics also compound the fluid loss from sweating. If you take any of these, expect a larger drop than the average person and rehydrate carefully.

Unstable or severe cardiac disease

Unstable angina, a recent heart attack, severe aortic stenosis, and poorly controlled blood pressure are situations where the transient heart-rate rise during the heat phase carries more risk. These warrant a conversation with a physician before sauna use, not a self-directed start.

Alcohol and dehydration

Alcohol lowers blood pressure and impairs the bodys ability to regulate temperature, so combining it with sauna stacks two pressure-lowering effects and is a documented risk. Dehydration from sweating without replacing fluids has a similar destabilizing effect on blood pressure.

Practical Note

If you take blood pressure medication, the simplest safeguard is to start with shorter, cooler sessions (10 to 15 minutes at the low end of the temperature range), hydrate before and after, and pay attention to how you feel standing up. Track your readings at home for a couple of weeks. For a fuller list of what can go wrong, see our infrared sauna side effects guide.

Pros

+Acute 7 mmHg systolic and diastolic drop demonstrated in a controlled study of at-risk adults
+KIHD cohort links frequent sauna use to ~46% lower hypertension risk over decades
+Clear, well-understood mechanism (vasodilation plus improved endothelial function)
+Waon far-infrared therapy showed measurable endothelial and BP benefit in heart failure patients
+Low cost and no dependency risk relative to many lifestyle interventions

Cons

−Most strong evidence is from traditional sauna, not infrared specifically
−Acute BP drop is temporary and not a treatment for established hypertension
−Blood pressure rises during the hot phase, a transient cardiac load
−Orthostatic hypotension risk, amplified by common BP medications
−Observational long-term data shows association, not proven causation

FAQ

Does infrared sauna lower blood pressure?+

Heat exposure does lower blood pressure, both acutely and over time, though most of the strongest data comes from traditional Finnish sauna rather than infrared specifically. In a 2018 study of 102 adults with cardiovascular risk factors, a single 30-minute sauna session dropped mean systolic blood pressure from 137 to 130 mmHg and diastolic from 82 to 75 mmHg, with the reduction still present 30 minutes after exiting. Over the long term, the Finnish KIHD cohort linked frequent sauna use to a markedly lower risk of developing hypertension. Infrared sauna shares the core mechanism (heat-driven vasodilation and improved endothelial function), so a similar but not identical effect is plausible.

Is infrared sauna safe if I have high blood pressure?+

For most people with stable, well-controlled hypertension, infrared sauna is generally considered safe, and the long-term evidence leans favorable. The cautions are specific. Blood pressure rises during the heat phase before it falls, which is a transient load on the heart. Many blood pressure medications, especially diuretics, beta blockers, and other vasodilators, amplify the post-sauna drop and the risk of orthostatic hypotension (dizziness on standing). Combining sauna with alcohol is a documented risk because both lower blood pressure. Anyone with unstable angina, recent heart attack, severe aortic stenosis, or poorly controlled blood pressure should clear sauna use with their physician first.

How much can sauna use reduce blood pressure?+

The acute effect of one session is roughly a 7 mmHg drop in systolic and a 7 mmHg drop in diastolic blood pressure in the minutes to first hour after exiting, based on the 2018 Laukkanen group data in higher-risk adults. The chronic, regular-use effect is harder to express as a single number because the strongest evidence is about hypertension risk rather than millimeters of mercury: in the KIHD cohort, men using a sauna 4 to 7 times per week had about a 46 percent lower risk of developing hypertension over follow-up versus once-weekly users. The acute drop is real but temporary; the long-term benefit appears to come from consistent, repeated exposure.

Written by

Aleksi Suoninen

Helsinki, Finland. Grew up with sauna as a daily ritual - Finland has more saunas than cars. Tests and writes about infrared sauna products from a Nordic perspective where heat therapy needs no justification.

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