Cold water swimming and your heart (British Heart Foundation)

Tier 1: Established: peer-reviewed research or government health authority
Publisher: British Heart Foundation · Published: August 15, 2026 · Accessed: August 15, 2026

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Claims this source supports

• Entering very cold water can lead to 'cold shock,' which can cause a faster heart rate, higher blood pressure, and shortness of breath; the colder the water, the harder the heart must work.
• Cold water swimming can lead to hypothermia and raise stress hormone levels, increasing the risk of abnormal heart rhythms (arrhythmias) and possibly even cardiac arrest.
• People with heart conditions should discuss cold water swimming with their doctor or nurse specialist before starting; cardiac physio guidance suggests water temperatures of 26-33°C (79-91°F) are safest, making heated pools a safer option.
• Safe-swimming tips: only swim when feeling well, allow at least an hour after a meal, enter and exit the water gently and gradually, warm up and cool down, and never swim alone – go with a friend or group.
• Regular cold water swimming can improve blood pressure and blood fat levels in those in good general health.