Health & Wellness

Sauna and the Immune System: What the Research Shows

An expert review of the evidence for sauna benefits on immune function — white blood cell production, respiratory health, and the practical implications for illness prevention.

By Wellness One Lifestyle · Published 2026-08-02 · Updated 2026-08-02

Sauna and Immune Function

The relationship between sauna use and immune function is one of the most practically relevant areas of sauna research. The evidence suggests that regular sauna use provides meaningful protection against common illnesses.

White Blood Cell Production

Heat stress triggers an increase in the production of white blood cells — the cells that identify and destroy pathogens. A single sauna session has been shown to increase white blood cell count by 20–30% for several hours after the session. Regular sauna use appears to maintain elevated baseline white blood cell levels.

Heat Shock Proteins

Heat stress triggers the production of heat shock proteins (HSPs), which play a critical role in immune function. HSPs help the immune system identify and respond to pathogens more efficiently, and protect cells from damage during infection.

Respiratory Health

The hot, humid air in a sauna (particularly with löyly) has beneficial effects on the respiratory system. It helps clear the airways, reduces congestion, and may reduce the severity of respiratory infections. Several studies have found that regular sauna users have better lung function and fewer respiratory infections.

The Finnish Evidence

A landmark Finnish study found that regular sauna users (4–7 times per week) had approximately 50% fewer colds than those who used the sauna once per week. The protective effect was dose-dependent — more frequent use provided greater protection.

Practical Implications

Regular sauna use — 3–4 times per week — appears to provide meaningful protection against common illnesses. The benefits are cumulative: the immune-boosting effects of regular sauna use build over time. A single sauna session during illness may provide some relief, but the preventive benefits require consistent, regular use.