Cold exposure causes blood vessels to constrict. A sudden cold-water shock can also cause rapid changes in breathing, heart rate, and blood pressure.

For healthy people, a brief cool rinse may simply feel invigorating.

But deliberately shocking the body with extremely cold water is a different matter.

Sudden cold-water immersion can produce a strong cardiovascular response, and people with existing heart problems may be more vulnerable.

That doesn’t mean every cool shower is dangerous.

The bigger concern is extreme and sudden temperature change, especially in people with cardiovascular disease.

A safer approach

If you enjoy cooler water, lower the temperature gradually rather than switching immediately from extremely hot to ice-cold.

There is no need to prove your toughness by standing under freezing water.

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3. Taking a Very Hot Shower When You Are Dehydrated

Dehydration can make heat-related dizziness worse.

Imagine someone who has spent the entire day sweating, drinking very little, and then takes a very hot shower.