When temperatures reach scorching levels and a dip in the sea isn't an option, a cold shower seems like a lifesaver. But according to Dr. Adam Taylor, professor of anatomy at Lancaster University, this approach isn't as effective as we think at cooling down the body. In an article for The Conversation, he explains why this happens, based on how our bodies work.
How to refresh the body naturally
The ideal temperature for normal body function is around 37°C. When the internal temperature rises above this level, the brain activates natural cooling mechanisms: it sends nerve signals to dilate blood vessels near the skin and stimulate sweating.
If the body remains at temperatures above 39–40°C for a long time, organ damage can occur. Therefore, the body uses several strategies to maintain thermal balance:
Heat radiation – about 60% of heat is released into the environment through thermal waves.
Sweating – when the environment is hotter than the body, sweating becomes the main cooling mechanism, removing about 22% of heat.
Evaporation, conduction, and convection – the body also loses heat through contact with air, water, or cold surfaces.
To aid this process, blood vessels near the skin's surface dilate, bringing more blood closer to the skin, which is usually cooler. The blood circulates to transfer heat from the core to the body's surface.
Cold or warm shower?
When faced with a major heat wave, the body's natural mechanisms are often not enough. Although a cold shower seems like an immediate relief, its effects can actually be the opposite:
Cold water constricts the blood vessels near the skin, reducing blood flow to the surface and blocking the body's natural cooling. The body "tricks itself" into thinking it no longer needs to cool down.
Very cold water does not cleanse the skin well, as it does not remove sebum and impurities like warm water does.
In some cases, sudden exposure to water at a temperature of around 15°C can cause "cold shock", a dangerous reaction that includes a sudden increase in blood pressure, irregular heartbeat and in extreme cases, life-threatening, especially in people with heart disease.
“Fortunately, these cases are rare and usually do not occur with a cold shower at home, but to be safe, it is best to avoid sudden exposure to ice water during very hot days,” Dr. Taylor emphasizes.
On the other hand, a very hot shower is not a solution either - water warmer than the body increases internal heat, increasing body temperature.
What is the best solution?
According to Dr. Taylor, a lukewarm shower or bath (around 26–27°C) is the best option on extremely hot days. This temperature helps blood move to the surface of the body to cool down, without constricting blood vessels or activating protective responses that conserve heat.
Lukewarm water also helps cleanse the skin and prevent problems like acne and blackheads by gently opening pores.
If you feel like you need instant coolness, you can try cold water, but lower the temperature gradually so as not to shock your internal temperature regulation system. This method helps the body adapt without stress and avoids negative effects.
