The sauna and body fluid balance.

Sauna bathing may affect the fluid, electrolyte and acid-base balance. In addition to sweating and thirst, a sauna bath also has effects on many endogenous regulatory mechanisms maintaining the balance between the fluid compartments and appropriate distribution of the circulating blood. Although the sauna-induced fluid loss is usually not very severe, its adequate replacement as early as possible is important. In practice, the most convenient and effective way is to replace the fluid loss by small liquid doses repeated frequently during the bathing. If a sauna bath is taken after heavy physical activity, the fluid compensation may be necessary already before bathing.