← All sources
Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis
2025 PLOS ONE systematic review and meta-analysis of 11 RCTs (n=3,177 healthy adults): acute cold-water immersion (≤15 °C, ≥30 s; mostly baths, one shower trial) showed large acute increases in pooled inflammation markers immediately and 1 h post-exposure, a significant reduction in stress at 12 h but not 0–48 h, null pooled immune effects at 0–1 h with narrative mention of longer-term cold-shower sickness-absence benefits, and signals for sleep quality and quality of life but not mood.
Scope
Eligible trials: healthy adults; cold shower, ice bath, or plunge at ≤15 °C for ≥30 s (acute or longer programs).
Pooled quantitative highlights (random-effects SMDs, pre vs post CWI)
- Inflammation markers: SMD +1.03 immediately post (95% CI 0.37–1.68; p < 0.01); SMD +1.26 at 1 h post (95% CI 0.59–1.94; p < 0.01) — authors frame as acute inflammatory response, not long-term chronic inflammation reduction.
- Stress: SMD −1.00 at 12 h post (95% CI −1.40 to −0.61; p < 0.01); no significant pooled stress change at 0, 1, 24, or 48 h.
- Immune function (immediate / 1 h): pooled not significant.
Narrative / secondary themes
- Sickness absence: narrative synthesis cites about 29% lower absence among cold-shower users — overlaps the standalone Buijze 2016 shower RCT indexed on this wiki; treat as supporting context, not a second independent primary estimate.
- Sleep quality & quality of life: directional improvements reported in synthesis; mood outcomes did not show a pooled signal.
How to use alongside other entries
- Cold exposure therapy (
cold-exposure): shower-inclusive evidence and pragmatic Buijze anchor. - Cold water immersion (
cold-plunge): most included trials were baths. - Cold exposure & inflammation (
cold-exposure-inflammation): acute marker increases here differ from chronic inflammatory-disease RCTs (e.g. metabolic syndrome cold acclimation) — keep time course in mind.
Limitations (authors)
Few RCTs, small individual trial sizes, limited population diversity; PROSPERO CRD42024500591.
Outcomes
- Effect Size (Cohen's d / SMD)1.03d (Cohen's d)
- Effect Size (Cohen's d / SMD)1.26d (Cohen's d)
- Effect Size (Cohen's d / SMD)-1d (Cohen's d)
- Narrative synthesis: ~29% reduction in sickness absence among cold-shower participants (ties to Buijze-style outcomes; not a separate pooled IRR in this paper).