In brief
Immersing yourself in cold water, from cold plunges to winter swims. It sets off a sudden cold shock response and carries real risks, while the evidence for benefits is scant.
- Never do a cold water swim on your own.
- If you try it, start slowly, then change out of wet clothes and warm up straight afterwards.
How it works
Cold water causes a sudden, rapid increase in breathing, heart rate and blood pressure, called the cold shock response. An involuntary gasp with your head under water can lead to drowning within seconds, and the rapid loss of heat can lead to hypothermia.
Some people believe cold water therapy strengthens the immune system and improves heart health, but the American Heart Association describes the evidence as scant. Heart specialists caution against it for anyone with a history of heart problems.
Connections
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Cold-water immersion has been studied for
- Heart and blood vessels Emerging
Cold water therapy is believed by some to improve heart health, but the evidence is scant, and the cold shock response makes the heart work harder.
Sources
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Summarised from the American Heart Association. Sources read on 16 October 2026. General education only, not medical advice. Spotted a mistake? Please tell us through the HuBu-Intel contact page.