The wellness trend of cold-water immersion (CWI), which includes ice baths and cold showers, continues to gain popularity as users report benefits ranging from stress reduction to immune system strengthening and recovery enhancement. This technique has been practiced for centuries in traditional cultures and is now increasingly adopted by a broader audience beyond athletes.
Individuals performing CWI in water around 10-15°C (50–59°F) may experience both nervous system activation and immune system changes.
Studies have documented its ability to help athletes recover from sports activities by decreasing muscle pain and inflammation, but the research reveals conflicting information about its impact on muscle growth. Additionally, the popularity of ice baths is not yet supported due to insufficient medical evidence. The systematic review and meta-analysis followed the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines and were registered under PROSPERO ID: CRD42024500591. Additional screening criteria required chest-level water immersion coverage and banned the study of protective garments. The research protocol was modified to include inflammation as a primary outcome variable.
The search covered ten research databases, combining “cold-water immersion” and related keywords found in CINAHL, Cochrane, MEDLINE, and the Web of Science. The screening process utilized Covidence software, where two independent reviewers checked study eligibility before a third party resolved any conflicting decisions.
Healthy adult participants (≥18 years) meeting the inclusion criteria had undergone CWI exposure to cold baths, showers, or plunges at temperatures below 15°C for thirty seconds or longer. The research evaluated three domains of outcomes: physical observations, psychological assessments, and brain functions. It excluded athletes from elite levels or those who had chronic illnesses.
The database search retrieved 3,481 studies, while 109 fulfilled the criteria for full-text evaluation. The evaluation process eliminated 98 studies because 70 articles failed to meet the inclusion criteria and 28 failed to fulfill design requirements. Eleven studies were included. Seven studies provided data, but only one of the authors participated in the response process. Five studies contained their data, which was extracted through the application Plot Digitizer. One study did not provide accessible data for evaluation.
Inflammation markers increased immediately after CWI (SMD: 1.03 [95% CI: 0.37, 1.68], p < 0.01) and remained elevated at the 1-hour mark (SMD: 1.26 [95% CI: 0.59, 1.94], p < 0.01), with a Grade B certainty level. The evidence showed no significant stress changes immediately post-CWI (SMD: −0.09 [95% CI: −0.45, 0.63], p > 0.05) and at 1 hour (SMD: −0.29 [95% CI: -0.66, 0.08], p > 0.05) or at 24 hours (SMD: −0.06 [95% CI: -0.50, 0.38], p > 0.05) or at 48 hours (SMD: 0.09 [95% CI]). No significant changes occurred in immune function immediately after immersion and at one hour post-exposure (SMD: −0.16 [95% CI: −0.82, 0.51], p > 0.05). The findings had D-level certainty.
This study evaluates the health consequences of cold-water immersion in healthy adults through a systematic review and meta-analysis. The results demonstrate that the acute inflammation occurs right after CWI administration and at the one-hour mark, which differs from earlier findings. The stress measures showed reduced levels at the 12-hour mark without any immediate variations. Participants reported improved sleep and quality of life; however, no significant changes in mood were observed.
The findings suggest that cold water immersion leads to potential stress relief and better sleep but do not provide conclusive research about its direct effect on immune function and inflammation. Studies with various participant backgrounds should evaluate CWI benefits for long-term safety at many timescales.
References: Cain T, Brinsley J, Bennett H, et al. Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis. PLoS One. Published January 29, 2025. doi:10.1371/journal.pone.0317615
