Do not expect cold showers to strengthen your immune system
In a trial of 3,018 people, cold showers reduced sickness absence by 29%, but did not reduce days of illness; that does not establish that people became ill less often. A 2025 review of 11 trials found temporarily increased inflammatory markers after cold exposure and no clear change in immune measures. Enjoyment is a different reason to take cold showers from treating them as a proven health investment; the notes address safety limits.
What it takes
No purchase is necessary, but 30–90 seconds of discomfort every day, especially in winter, takes resolve. Cardiovascular risk also matters.
What you may gain
A Dutch randomized trial enrolled 3,018 people and compared normal showers with ending a hot shower with 30, 60, or 90 seconds of cold water. The cold-shower groups reported 29% fewer sickness absences, incidence rate ratio 0.71, but no reduction in total days of illness. Quality of life, productivity, and anxiety showed no meaningful improvements. A 2025 systematic review included 11 randomized trials involving 3,177 people. It found increased inflammatory markers immediately and one hour after exposure, no clear immune changes, and lower stress only at the 12-hour measurement. The number of trials was small. The attraction is that something free and unpleasant feels as though it must be doing you good.
Context & considerations
Fewer sickness absences were an observed result, but they could reflect going to work while ill rather than getting ill less often. Athletic recovery is outside this entry’s scope. The original text regards voluntary cold showers in healthy people as acceptable; that should not be read as establishing that cold exposure is harmless for everyone, especially people with cardiovascular conditions.
Research & references
Buijze GA et al. (2016). The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial. PLOS ONE. https://doi.org/10.1371/journal.pone.0161749; Cain T et al. (2025). Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis. PLOS ONE. https://doi.org/10.1371/journal.pone.0317615.