Does Regular Sauna Use Lower Your Risk of Colds and Respiratory Illness?

"Does sauna use help you get sick less often" has been asked — and studied — since at least 1990. The research has only gotten more rigorous since then, culminating in a long-term Finnish cohort study that's one of the largest of its kind.

What the research looked at

The foundational study, from 1990, assigned 25 volunteers to regular sauna bathing and 25 to a control group, tracking cold frequency, duration, and severity over six months — a small but genuinely controlled early trial. Decades later, the Kuopio Ischaemic Heart Disease (KIHD) cohort study followed 2,210 Finnish men aged 42–61 for a median of about 25 years, comparing sauna frequency against diagnosed respiratory diseases including COPD, asthma, and pneumonia.

What they found

In the 1990 study, the sauna group had meaningfully fewer colds than controls, especially in the final three months of the study. The much larger and more recent KIHD cohort found a clear dose-response pattern: compared to men who used a sauna once a week or less, those bathing 2–3 times a week had a 27% lower risk of respiratory disease, and those bathing 4 or more times a week had a 41% lower risk. Pneumonia risk specifically was reduced even more — by 33% and 47% respectively across the same frequency groups.

What this means in practice

Two studies three decades apart point the same direction, with the more recent and much larger cohort showing a clear dose-response relationship — more frequent sauna use, lower respiratory illness risk. This is observational data (not a randomized trial), so it shows a strong association rather than definitive proof of cause and effect, but it's a consistent enough pattern to be a genuinely interesting reason to make sauna use a regular habit rather than an occasional treat.