Large prospective cohort studies show a dose-dependent relationship between regular sauna bathing and a lower risk of premature mortality, particularly through beneficial effects on the cardiovascular system. However, the evidence is exclusively observational, and confounding factors such as a more active and healthier lifestyle among frequent sauna users may distort the results. A causal relationship has therefore not yet been conclusively established.
Large prospective cohort studies show that people who regularly take sauna baths have a lower risk of premature death, and this association is dose-dependent: the more frequently someone uses a sauna, the greater the measured benefit. These are, however, observational data. A direct cause-and-effect relationship has not yet been proven, partly because healthier and more physically active people tend to report more frequent sauna visits in the first place (PMID: 34363927, 37270272, 30077204).
The strongest evidence concerns the heart and blood vessels. Multiple studies link regular sauna use to a lower risk of high blood pressure, cardiovascular disease, and arterial stiffness. Possible explanations include improved blood vessel function and favourable changes in blood lipids. The quality of the evidence is reasonable, but causality has not been conclusively established here either (PMID: 30077204, 33792402, 37270272, 33513711).
For the brain and lungs, the indications are weaker. Observational studies suggest an association between regular sauna bathing and a lower risk of dementia and certain lung diseases, but the evidence base is limited. Confounding factors such as overall health and lifestyle may distort the results (PMID: 30077204, 37270272).
Sauna appears most effective as part of a broader healthy lifestyle. Combining it with regular physical exercise seems to strengthen the protective effect on the heart and blood vessels. Using sauna as a substitute for exercise has not been studied and is not recommended (PMID: 37270272).
In patients with rheumatic conditions (including rheumatoid arthritis and osteoarthritis), there are indications that sauna therapy, particularly infrared sauna, used as a supplement to standard treatment can reduce pain, stiffness, and inflammatory markers, and can improve mobility. The evidence is limited and the optimal treatment duration and long-term safety remain unclear (PMID: 40202605, 30077204).
For healthy adults, sauna is considered safe. Dehydration is a well-known immediate risk. In people with certain cardiovascular conditions, rheumatic diseases, or other chronic conditions, caution is warranted and medical advice is necessary. Long-term safety in specific patient groups and the optimal frequency and session duration have not yet been sufficiently studied (PMID: 34363927, 40202605, 30077204).
All claims are based on observational cohort studies and reviews (PMID: 34363927, 37270272, 30077204, 33792402, 33513711, 40202605). No randomised controlled trials on mortality are available. Causal conclusions are therefore not possible.