Don’t force yourself to take cold showers just to “boost immunity”

12. Don’t force yourself to take cold showers just to “boost immunity”

Cost: No cost at all. It requires enduring discomfort for 30 to 90 seconds each day; staying consistent in winter demands real willpower. People with cardiovascular conditions should be extra cautious, as cold exposure poses certain risks for them.

In plain terms: In a large clinical trial, individuals who took cold showers reported 29% fewer sick days, yet their total days missed due to illness remained unchanged — meaning they were not actually getting sick less often. A recent evidence synthesis combining multiple trials found that cold showers temporarily raise bodily inflammation markers without measurably altering overall immune function. Take cold showers if you enjoy them, but don't treat them as an effective health investment.

Benefit: A randomized controlled trial conducted in the Netherlands enrolled 3018 participants. After a hot shower, they were asked to rinse under cold water for 30, 60, or 90 seconds. This group ended up taking 29% fewer sick days compared to the control group (IRR 0.71). Yet the study explicitly notes that there was no significant difference between groups regarding total sick days. No meaningful improvements were observed in quality of life, work productivity, or anxiety levels either. The 2025 review analyzed 11 randomized trials involving 3177 participants overall. It found that both immediately after and one hour post‑shower, inflammatory markers rose temporarily, while immune indicators stayed unchanged. Only at the 12‑hour mark did stress levels drop slightly. The authors themselves point out that the evidence is limited by the small number of trials and modest sample sizes. The practice seems cost‑effective only because it costs nothing, and because the intuitive belief that “enduring hardship brings benefits” makes it appealing.

Evidence grade: B

Sources: 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>

Notes: Controversy: The 29% reduction in sick‑day frequency is real and unlikely to be a coincidence. Yet total illness days didn’t decrease, so it’s more plausible that participants simply kept going to work despite being unwell rather than actually getting sick less often. Using cold water for post‑exercise recovery among athletes is a separate issue and falls outside the scope of this discussion. For healthy individuals, cold showers pose no harm; this note simply warns against viewing them as a health‑promoting investment.