Limited evidence suggests cold showers may reduce sickness absence by 29%, but immune function effects remain unclear.
A 2025 systematic review found that cold water immersion showed no significant immediate effects on immune function, but narrative analysis suggested longer-term benefits including a 29% reduction in sickness absence among cold shower users. The evidence base is limited by few high-quality trials, small sample sizes, and short follow-up periods, making definitive conclusions about immunity boosting difficult.
RCTs found
527 in PubMed, 11 included in meta-analysis
Largest trial
3,177 participants across 11 studies
Date range
Recent systematic review (2025)
Effect size
small to none for direct immune measures