When Heat Becomes a Health Risk: How Hot Weather Affects the Body and How to Protect Yourself

Summer in Barcelona means sunshine, the sea, long evenings and life outdoors. However, high temperatures are not simply a matter of comfort. When hot weather lasts for several days, temperatures remain high even at night, or high humidity is added to the equation, the body may find it increasingly difficult to maintain its normal internal temperature.

Extreme heat places stress on the entire body. It can lead to dehydration, heat exhaustion or life-threatening heatstroke, and it can also worsen existing heart, lung and kidney conditions, as well as diabetes.

The human body tries to maintain its internal temperature within a relatively narrow range. When we become hot, the blood vessels near the skin widen and sweating increases. As sweat evaporates, it helps cool the body.

However, this mechanism has its limits. When humidity is high, sweat evaporates more slowly, making it more difficult for the body to cool down effectively. At the same time, the heart has to work harder to pump more blood towards the surface of the body. Sweating also causes the loss of water and minerals, and if fluids are not adequately replaced, the volume of circulating blood may decrease.

This can result in tiredness, weakness, headaches, dizziness, muscle cramps or a drop in blood pressure. Prolonged heat exposure may also place additional strain on the kidneys and worsen cardiovascular, respiratory and metabolic conditions.

It Is Not Just About the Temperature

The way heat affects a person does not depend only on the temperature shown on a thermometer. Other important factors include:

• air humidity,
• direct sunlight,
• air circulation,
• physical activity,
• clothing,
• the duration of heat exposure,
• access to rest and cooling,
• a person’s health and medication.

In direct sunlight, the perceived heat exposure can be significantly higher than in the shade. The risk also increases when high temperatures persist throughout the night. The body then has less opportunity to recover, allowing heat stress to gradually accumulate.

Heat can affect anyone, but some people have a reduced ability to regulate their body temperature or to avoid exposure to hot conditions.

Particular care should be taken by:

• older adults,
• infants and young children,
• pregnant women,
• people with heart, lung or kidney disease,
• people with diabetes,
• patients with reduced mobility or neurological conditions,
• people taking certain medications,
• people working or exercising outdoors,
• tourists who are not accustomed to the local climate,
• people living alone or without an effective way to cool their homes.

Older age, chronic illness and certain types of medication may affect thirst, sweating, blood pressure, the body’s fluid balance or its ability to respond to overheating. However, medication should not be stopped or the dosage changed without medical advice during hot weather. Anyone with concerns should consult their doctor.

The first signs of overheating may appear relatively mild. They can include:

• unusually heavy sweating,
• intense thirst,
• tiredness and weakness,
• headache,
• nausea,
• dizziness,
• muscle cramps,
• a rapid heartbeat,
• feeling faint.

These symptoms may indicate heat exhaustion. The affected person should stop their activity, move to a cooler environment, loosen their clothing, cool their body and gradually replace lost fluids.

Confusion, loss or alteration of consciousness, seizures, collapse, a very high body temperature or a sudden change in behaviour may be signs of heatstroke. Heatstroke is an acute, potentially life-threatening condition that requires immediate medical assistance.

1. Drink Regularly, Not Only When You Feel Thirsty

During hot weather, it is advisable to drink small amounts regularly throughout the day. The sensation of thirst does not always accurately reflect the body’s actual fluid requirements, particularly in older adults.

Water is generally the best option. During prolonged physical activity or heavy sweating, electrolytes may also need to be replaced. Alcohol can worsen dehydration, while very sugary or highly caffeinated drinks are not ideal as the main source of fluids.

However, there is no universal amount of water that is suitable for everyone. People with heart or kidney conditions who have been advised to limit their fluid intake should follow the individual recommendations of their doctor.

2. Move Activities to the Cooler Parts of the Day

Exercise, long walks, gardening and physically demanding journeys are best planned for the morning or evening. During the hottest hours of the day, reduce physical exertion and seek shade whenever possible.

Take regular breaks when spending time outdoors. If you develop a headache, weakness, nausea or dizziness, do not continue the activity in an attempt to simply “push through it.”

3. Cool Your Body, Not Just the Room

During the day, close blinds, shutters or curtains on the side of the building exposed to direct sunlight. Ventilate the room mainly when the air outside is cooler than the air indoors. A lukewarm shower, a damp towel, lightweight clothing and time spent in an air-conditioned or otherwise cool space can also help.

A fan may provide a feeling of relief, but during extremely high temperatures, it may not be sufficient on its own to prevent overheating.

4. Choose Lightweight Clothing and Remember Sun Protection

Wear lightweight, loose-fitting and breathable clothing. When spending time outdoors, use a hat, sunglasses and broad-spectrum sunscreen. Protection from ultraviolet radiation and the prevention of overheating are two different issues, but both are important during the summer.

5. Check on Vulnerable People Around You

During a heatwave, contact older relatives, neighbours and people with chronic illnesses, especially if they live alone. Make sure they have enough water, that their home is not becoming dangerously hot and that they have not developed any unusual symptoms.

Never leave a child, a dependent person or an animal inside a parked vehicle, even for a short period of time.

Listen to Your Body Before It Forces You to Stop

Overheating does not usually begin dramatically. It is often preceded by tiredness, headache, difficulty concentrating, irritability, nausea or the feeling that an ordinary activity has suddenly become much more demanding.

This is the best moment to stop and rest. Moving to a cooler place, taking a break and replacing fluids can prevent early symptoms from developing into a more serious condition.

Hot weather is a normal part of summer in Spain, but it should not be underestimated, particularly in children, older adults, pregnant women and people with chronic illnesses. Planning the day carefully, drinking regularly and recognising warning signs early can significantly reduce the health risks associated with heat.

If you need a medical consultation, examination or assistance finding the right specialist during your stay in Barcelona, Barcelona Medical Consulting can help organise your medical care from the initial contact through to follow-up care.

We coordinate communication with leading private hospitals and medical specialists, arrange appointments and provide additional services such as medical interpretation and hospital accompaniment.