Cold-water immersion cools heatstroke fastest

Cold-water immersion is the fastest supported treatment and should be started before transport when feasible.
*Systematic review of heterogeneous studies; Level 2a (OCEBM).

Citation

Wahid F, Ahmed S, Islam MT, et al. Heatstroke Over the Past Decade: Risk Factors, Long-Term Health Consequences, and Preventive Measures. Journal of General Internal Medicine. 2026. doi:10.1007/s11606-026-10594-1

Background

Heatstroke can rapidly cause brain, kidney, heart, and other organ injury. Rising heat exposure and aging populations make prevention, early recognition, and rapid cooling increasingly important.

Patients

People diagnosed with classic or exercise-related heatstroke. Excluded studies included animal studies, case reports, case series with fewer than 10 patients, non-English publications, and studies without clinical outcomes.

Intervention

Risk-factor assessment, cooling methods, and wearable or prediction technologies.

Control

Usual care, other heat-illness groups, healthy controls, or alternative cooling methods.

Outcome

Heatstroke risk, long-term organ disease, death, cooling rate, and prediction accuracy.

Follow-up Period

Hospital discharge to 14 years, depending on study.

Results

FindingResultCertainty
Exercise-related heatstroke in runners younger than 305.5-fold higher incidence than ages 50–59Moderate
Neuropsychiatric disorders7.69-fold higher adjusted odds of heatstrokeHigh
Heart attack after heatstroke7.43-fold higher adjusted risk versus other heat illnessLow
Chronic kidney disease after heat injury4.35-fold higher adjusted riskLow
Cold-water immersion cooling0.14–0.22°C/min; faster than cold intravenous fluidModerate

The review used narrative synthesis rather than pooled analysis because study designs and outcome reporting varied widely. Cold-water immersion is the accepted preferred field treatment when available.

Limitations

Evidence was limited by English-only studies, varied definitions and follow-up, no meta-analysis, and some volunteer-based cooling studies that may not fully match real emergencies. Prediction models looked promising but often used very small event samples.

Funding

No external funding reported.

Clinical Application

Treat suspected heatstroke immediately: cool first, transport second. Use cold-water immersion when feasible and target prevention to athletes and vulnerable older adults.