Heat and blood pressure: what 15 studies add up to
A review pooled the trials of regular heat on blood pressure and blood vessels. Blood pressure came down a few points, and vessels widened a little better.
Worth knowing: The search ended in September 2020. Hamaya’s 2025 review includes newer randomized evidence and reaches a more cautious conclusion; both are in this library.
The short version
This review pooled 15 studies in which people had repeated heat sessions, from 10 to 36 of them, and compared them with people who did not. Systolic and diastolic blood pressure both came down by about 4 points on average, and blood vessels widened a little better. Resting heart rate did not change. The reviewers rated their certainty moderate for blood pressure and low for blood vessels. The studies were small and used different kinds of heat, and most were not a Finnish sauna.
Keep in mind
Small studies with different kinds of heat, in different groups of people. A few points of blood pressure over weeks, not a long-term result.
What they found
Systolic blood pressure was 3.9 mmHg lower with heat (95% confidence interval 0.7 to 7.2, from 10 studies). Diastolic blood pressure was 3.9 mmHg lower (1.6 to 6.1, from 9 studies).
Flow-mediated dilation, a measure of how well an artery widens, was 1.95 percentage points higher (0.14 to 3.76, from 5 studies).
Resting heart rate did not change. The reviewers rated the certainty moderate for blood pressure and heart rate, and low for artery widening.
What this means for your practice
Regular heat may lower blood pressure a little over a few weeks. If you have high blood pressure, heat is not a replacement for treatment.
This does not establish a sauna routine to follow.
Methods and limitations
What the researchers did
The reviewers searched four databases up to September 2020 and screened 4,522 titles. Fifteen studies compared repeated heat therapy with a control condition and measured blood pressure or blood vessel function.
The studies included healthy people and patients. Heat sessions lasted 30 to 90 minutes, and people had 10 to 36 of them.
The reviewers combined the results and rated how certain each finding was with GRADE, the same approach The Study adapts for its scores.
How much can this tell us?
This was an encouraging early summary. A newer randomized-trial review in this library found no clear overall improvement in artery function or blood pressure, although whole-body heating showed a possible blood-pressure benefit.
The effect is modest: about 4 points. That is worth having, but it is smaller than what blood pressure medicine typically does.
The studies were small and varied: hot-water immersion, sauna and other heat, in healthy people and patients. The result says little about which kind of heat, how hot, or how often. A later trial of Finnish sauna in people with heart disease, also in this library, found no change.
What makes it useful
- Pooled 15 studies, rated with GRADE
- A consistent direction for blood pressure
- Reports its own certainty for each outcome
What limits it
- Small studies, 10 or fewer for each measure
- Mostly hot water and other heat, not Finnish sauna
- Mixed groups: healthy people and patients
- Weeks, not years
Where this study fits
Where this study fits
We score claims, not single studies. This one is part of the evidence for:
Regular heat keeps blood vessels healthy. Not supported
Low certaintyNo effect foundBody signals
A few weeks of regular heat lowers blood pressure. Some support
Low certaintySmall effectBody signals
Read the original
Pizzey FK, Smith EC, Ruediger SL, Keating SE, Askew CD, Coombes JS, Bailey TG. The effect of heat therapy on blood pressure and peripheral vascular function: A systematic review and meta-analysis. Exp Physiol. 2021;106(6):1317-1334.
DOI 10.1113/EP089424 · PubMed 33866630