What is Cold Water Shock?
It’s the body’s reaction when immersed in cold water.
How does it happen and what are the cold water shock symptoms?
Cold water shock causes the blood vessels in the skin to close, which increases the resistance of blood flow. Heart rate is also increased. As a result the heart has to work harder and your blood pressure goes up. Cold water shock can therefore cause heart attacks, even in the relatively young and healthy.
The sudden cooling of the skin by cold water also causes an involuntary gasp for breath. Breathing rates can change uncontrollably, sometimes increasing as much as tenfold. All these responses contribute to a feeling of panic, increasing the chance of inhaling water directly into the lungs.
This can all happen very quickly: it only takes half a pint of sea water to enter the lungs for a fully grown man to start drowning. You could die if you don’t get medical care immediately.
Why is cold water shock dangerous?
Anything below 15°C is defined as cold water and can seriously affect your breathing and movement, so the risk is significant most of the year.
Average UK and Ireland sea temperatures are just 12°C. Rivers such as the Thames are colder – even in the summer.