What does extreme heat do to the human body?

Hot summer weather poses health risks for everyone, but certain groups face greater danger. Understanding how heat affects the body can help people stay safe during heatwaves. Some individuals are significantly more vulnerable than others.

As temperatures rise during summer, the human body faces real physiological challenges. Heat affects everyone, but the severity of those effects depends on age, health conditions, and how quickly a person can cool down.

How the body responds to heat

When exposed to high temperatures, the body works hard to maintain a safe core temperature. It does this primarily through sweating and redirecting blood flow toward the skin. This process strains the cardiovascular system, making the heart pump harder to keep things running smoothly.

Dehydration is one of the most common consequences of hot weather. As the body loses fluids through sweat, blood volume decreases, which can lead to dizziness, confusion, muscle cramps, and in severe cases, heat stroke — a life-threatening condition requiring immediate medical attention.

Who faces the greatest risk

While anyone can be harmed by extreme heat, certain groups are far more vulnerable. The elderly, young children, pregnant women, and people with chronic illnesses such as heart disease, diabetes, or respiratory conditions face a significantly elevated risk. People who work or exercise outdoors are also at higher danger.

Heat stroke occurs when the body's temperature regulation fails entirely, pushing core temperature above 40°C. Symptoms include confusion, loss of consciousness, and hot, dry skin. It is a medical emergency. Health experts consistently advise staying hydrated, avoiding peak sun hours, wearing light clothing, and seeking air-conditioned spaces during heatwaves to reduce the risk of heat-related illness.