Far-Infrared Saunas for Treatment of Cardiovascular Risk Factors: Summary of Published Evidence

Executive summary

This is the most directly relevant entry in the library for anyone buying an infrared sauna, because it is one of very few reviews that examines far-infrared cabins rather than traditional Finnish saunas.

The author searched Web of Science, EBSCO, Ovid MEDLINE, Ovid HealthSTAR and EMBASE for far-infrared sauna studies in humans published in English. The search yielded nine relevant papers, described as level I or level II evidence. Four supported use in congestive heart failure and five in people with coronary risk factors.

The conclusions are graded and deliberately unflattering. There is limited moderate evidence for normalising blood pressure and treating congestive heart failure; fair evidence from a single study for chronic pain; weak evidence from a single study each for chronic fatigue syndrome and for obesity; and - importantly - consistent fair evidence refuting claims about cholesterol reduction.

The review opens by noting that manufacturers claim numerous health benefits while the published evidence to substantiate those claims is limited. Fifteen years later that observation remains the most useful thing a buyer can take from it.

This entry exists mainly to give a buyer a fair comparison. Set it beside the Finnish cohort studies and the difference in the size and quality of the two evidence bases is immediately visible.

Why this research matters

Almost every claim made for an infrared cabin borrows its authority from traditional sauna research. This review is what the infrared-specific evidence base actually looked like when someone went and counted it.

It also demonstrates something rare and valuable: a review that explicitly refutes a specific marketing claim. The cholesterol claim still circulates, and this is the citation that contradicts it.

What the researchers found

The review reports the following graded conclusions:

Limited moderate evidence supporting far-infrared sauna efficacy in normalising blood pressure and in treating congestive heart failure. Fair evidence, from a single study, supporting use in chronic pain. Weak evidence, from a single study, in chronic fatigue syndrome. Weak evidence, from a single study, for obesity.

And consistent fair evidence to refute claims regarding the role of far-infrared saunas in cholesterol reduction. That is a finding against a commonly marketed benefit, not an absence of evidence for it.

Numerical effect sizes, confidence intervals and participant numbers for the individual studies are not reported in the review abstract and are therefore not reproduced here.

What the results mean

For the strongest claims in this review - blood pressure and congestive heart failure - the wording is 'limited moderate evidence'. That means a small number of studies pointing in a consistent direction, not a settled result. Congestive heart failure is also a clinical population under medical supervision, not a general wellness context.

For chronic pain, chronic fatigue syndrome and obesity, each conclusion rests on one study. A single small study is a reason to investigate further, not a basis for a purchase.

The cholesterol conclusion is the clearest thing here and it runs the other way: the evidence available refuted the claim. A buyer shown a cholesterol benefit for an infrared cabin should treat it as unsupported.

Strengths and limitations

Strengths

• Examines far-infrared specifically rather than conflating it with traditional sauna bathing.
• Grades the strength of evidence for each outcome rather than listing studies uncritically.
• Explicitly reports a refuted claim, which is unusual and valuable.
• Published in a peer-reviewed clinical journal aimed at practising physicians rather than consumers.
• Searched five databases.

Limitations

• Only nine papers met inclusion, so the whole review rests on a very small literature.
• Narrative rather than systematic: no pre-registered protocol, no formal risk-of-bias assessment, no meta-analysis.
• Several conclusions derive from a single study each.
• English-language restriction.
• Now more than fifteen years old.
• Much of the underlying work was conducted with a limited range of far-infrared systems, so generalisation across cabin designs is uncertain.
• Clinical populations in several included studies limit generalisability to healthy home users.

Evidence in context

The far-infrared literature has grown modestly since 2009 but has not been consolidated by a major systematic review or meta-analysis with the standing of the Cochrane or Mayo Clinic Proceedings work available for traditional sauna bathing.

Meanwhile the traditional-sauna evidence base expanded considerably, which has widened rather than narrowed the gap between the two. A 2018 systematic review of dry sauna bathing covering 40 studies found most reported benefit while noting that only 13 were randomised and most were small - and that review is still not about infrared cabins.

The honest summary is that infrared-specific evidence remains thin, and that this has not changed much in fifteen years.

Related research

1. Association between sauna bathing and fatal cardiovascular and all-cause mortality events Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. JAMA Internal Medicine 175(4):542-8. 2015. PMID 25705824; doi:10.1001/jamainternmed.2014.8187.The traditional-sauna cohort study whose findings are most often, and incorrectly, transferred to infrared cabins.
2. Clinical effects of regular dry sauna bathing: a systematic review Hussain J, Cohen M. Evidence-Based Complementary and Alternative Medicine 2018:1857413. 2018. PMID 29849692; PMC5941775; doi:10.1155/2018/1857413.A systematic review of dry sauna bathing that illustrates how much larger the traditional-sauna literature is.
3. Cardiovascular and other health benefits of sauna bathing: a review of the evidence Laukkanen JA, Laukkanen T, Kunutsor SK. Mayo Clinic Proceedings 93(8):1111-1121. 2018. PMID 30077204; doi:10.1016/j.mayocp.2018.04.008.A broad review of sauna bathing evidence, useful for direct comparison of evidence volume and quality.
4. Before-bedtime passive body heating by warm shower or bath to improve sleep: a systematic review and meta-analysis Haghayegh S, Khoshnevis S, Smolensky MH, Diller KR, Castriotta RJ. Sleep Medicine Reviews 46:124-135. 2019. PMID 31102877; doi:10.1016/j.smrv.2019.04.008.Passive body heating and sleep - a separate heat-exposure question with its own, better-designed evidence.