As the UK swelters in a heatwave, a GP has explained the key differences between heat exhaustion and sunstroke symptoms, and when you need to call 999. According to the NHS, heatstroke is more serious than heat exhaustion, which can often improve with rest, cooling down and drinking fluids.
What is heat exhaustion and sunstroke?
Heatstroke is a medical emergency that occurs when the body becomes dangerously overheated and is unable to cool itself down. It can happen during periods of extreme heat or following strenuous exercise and, without prompt treatment, can cause severe damage to the brain and other vital organs.
Meanwhile, heat exhaustion occurs when the body becomes overheated and loses too much water and salt, often because of hot weather or strenuous physical activity.
UK heatwave and warnings
The Met Office has said the UK is on course for its hottest summer on record, with only average conditions needed for the rest of August to beat the record set just last year. Some parts of the country are facing a fifth heatwave of the summer, with amber extreme heat warnings in place for parts of England on Thursday when temperatures could hit 38C in some spots.
Claire Nevinson, a pharmacist at Boots, shared what happens to your body in hot weather. She said: "Our body constantly regulates itself at a core temperature of around 37°C. As the surrounding temperature rises, the body tries to cool itself through increasing blood flow to the skin and through sweating. It's this sweating that causes our body to lose water, but if this lost water isn't replaced, the drop in fluid volume can quickly affect your energy levels, concentration and overall wellbeing – sometimes leading to heat exhaustion or heatstroke."
Recognising the signs
Claire recommended staying hydrated throughout the day to prevent the risk of heat exhaustion. She said: "Early signs of dehydration include a dry mouth or lips, thirst, headaches, dizziness, tiredness and dark yellow, strong-smelling urine. However, it's important to note that symptoms vary by age. Severe symptoms like confusion, continuous dizziness when standing, seizures, or loss of consciousness require urgent medical help by calling 999 or going to A&E."
Dr Angela Rai, GP at The London General Practice, spoke to Express.co.uk about heat exhaustion, sunstroke, and the associated health risks. "Being exposed to too much heat can lead to you feeling generally unwell, lacking in energy and feeling dizzy or sick," said Dr Rai. This is typically an indication of heat exhaustion, which may also trigger other alarming symptoms. Should you spot any signs of heat exhaustion, it's vital to take the correct steps to stop it developing into sunstroke. "Sunstroke is the most serious form of heat injury and is a medical emergency," warned Dr Rai.
Symptoms and what to do
Heat exhaustion symptoms include headaches, loss of appetite, nausea, body temperature about 38°C, excessive sweating, pale clammy skin, and feeling very thirsty. Claire added: "Heat exhaustion occurs when the body overheats and it frequently develops alongside dehydration. While it shares similar warning signs with dehydration, the key differentiator to heat exhaustion is marked by additional physical symptoms – specifically muscle cramps, feeling or being sick, and a high body temperature. It more commonly affects vulnerable groups, such as older adults, people with chronic health conditions and those taking certain medications. To help manage and prevent heat exhaustion you should focus on actively cooling the body. This includes taking cool showers or using a damp cloth, eating lighter meals, drinking plenty of fluids and keeping indoor air circulating with fans, air conditioning, or open windows. If someone continues to show signs of heat exhaustion despite efforts to cool them down, they are at risk of heatstroke, and you should seek urgent medical help by contacting NHS 111 or calling 999."
Signs of sunstroke include body temperature above 40°C, fast breathing, shortness of breath, feeling unwell after resting and cooling off, feeling confused, having a seizure, loss of consciousness, and not being responsive. Dehydration sets in, resulting in electrolyte imbalances and, in more severe cases, complications with kidney function, cardiac abnormalities and dangerous heart rhythms. There could even be "damage to brain tissue due to brain haemorrhage or swelling".
If you are uncertain whether you are suffering from heat exhaustion or the early stages of sunstroke, dial 111. Always follow the guidance of the emergency response team, who may advise you to attend hospital.
