Expert reveals the hidden signs of heat illness as Portsmouth experiences heatwave

As Portsmouth experiences a severe high temperature warning, an expert warns that heat-related illness is a real and preventable danger. The expert also offers heat-safety tips for football supporters heading to the FIFA World Cup, where high temperatures are expected in several host cities.

Owena Cleary, Director of CPR First Aid Training, sets out the key differences between heat cramps, heat exhaustion, and heatstroke, explains what warning signs to watch for, and offers practical advice for fans, players, and everyday people navigating a hot summer. 

The types of heat-related illnesses

Not all heat-related illnesses are the same, and it is important to understand the different types of illnesses that can affect people. Heat cramps are the mildest form of heat illness. The symptoms include painful muscle spasms, usually in the legs or abdomen, caused by fluid and electrolyte loss through sweating. If someone has heat cramps, they are still alert and their body temperature will remain normal. A person who is experiencing heat cramps should seek shade, rest, and drink something with electrolytes. 
When the body can no longer regulate its temperature, a person can begin to experience heat exhaustion. Their temperature can rise to 40°C, and they can appear confused or feel like they might faint. The other symptoms you might feel or witness are heavy sweating, clammy skin, nausea, headache, or dizziness. To relieve heat exhaustion, a person should relocate to a cool environment immediately and be laid down, with slightly elevated legs. If they are still conscious, they should be given water. If their symptoms do not improve, call for emergency help. 
If heatstroke is suspected, it needs to be treated as a medical emergency. The body's temperature can rise above 40°C, and without prompt treatment, heatstroke causes organ failure and can be fatal. 
There are two types of heatstroke that people need to be aware of. Classic heatstroke typically affects older adults, young children, or those with underlying health conditions during prolonged heat exposure. Exertional heatstroke occurs in otherwise healthy people during intense physical activity in the heat, which makes it especially relevant to athletes. 
During heatstroke, a person’s skin will be hot and red. If they are experiencing classic heatstroke, they might not be sweating at all. They might be nauseous, confused, have slurred speech, or have a seizure. Heatstroke is not a “wait around and see” illness; emergency services need to be called immediately. While you are waiting for help, cool the person by applying ice packs to the neck, armpit, and groin, fan them while misting cool water, and immerse them in cool water if possible.  

Heat-related illness prevention tips  

Cleary says, "Most people know that hydration is one of the most important heat-safety strategies, but it is often misunderstood." During prolonged or intense activity in hot conditions, drinking excessive amounts of plain water without replacing sodium can, in rare cases, contribute to hyponatraemia, a condition in which blood sodium levels become dangerously low. For activities lasting more than an hour, especially when sweating heavily, you should be replacing electrolytes as well as fluids. Replacement options include sports drinks, coconut water, electrolyte solutions, and natural sodium-containing foods. 

The clothes you wear can greatly affect your day outdoors. If you plan to spend time in hot temperatures, wear loose-fitting, light-coloured clothing since it will reflect solar radiation rather than absorbing it. Wearing synthetic moisture-wicking fabrics can help, but in dry heat, a loose cotton or linen layer can be more effective because it traps a layer of cooler air against the skin. 

Using sun cream not only reduces your risk of burns and skin cancer, but also supports your body’s ability to cool itself. Sunburn reduces the skin’s ability to shed heat, which makes you feel hotter.  

Be cautious about drinking alcohol in the heat because it is a diuretic and impairs the body's ability to sense that it is overheating. You should also try to avoid being outside during the hottest part of the day, typically between 11am and 3pm.