When the weather turns hot, the body tries to keep its core temperature within a safe range. It does this mainly by increasing blood flow to the skin and producing sweat, which cools the body as it evaporates.
Why heat can become a problem
These cooling mechanisms use water and place extra demand on the circulation. If a person loses more fluid than they replace, or if the environment is so hot and humid that sweat cannot evaporate effectively, body temperature can rise and heat illness can develop.
Who is more vulnerable?
Anyone can become unwell in extreme heat, but risk is higher for older people, babies and young children, people with certain heart, lung, kidney or neurological conditions, those taking medicines that affect hydration or temperature regulation, and people doing strenuous work or exercise outdoors.
Heat exhaustion and heatstroke
Heat exhaustion can involve heavy sweating, weakness, dizziness, headache, nausea, thirst and feeling faint. Moving to a cooler place, resting and replacing fluids can help.
Heatstroke is a medical emergency. Confusion, loss of coordination, collapse, seizures or very high body temperature are warning signs that urgent medical help is needed.
Practical precautions
- Drink regularly and avoid waiting until you are very thirsty.
- Reduce strenuous activity during the hottest part of the day.
- Use shade, light clothing and cooler indoor spaces where possible.
- Check on people who may struggle to recognise or respond to heat.
Most people cope well with ordinary summer weather, but extreme heat deserves respect. The important distinction is between discomfort and signs that the body is no longer regulating temperature effectively.
Source
NHS guidance on hot weather, heat exhaustion and heatstroke.
