As temperatures soar across the UK, health experts are warning about the dangers of dehydration, a common but potentially serious condition during heatwaves. While thirst and a dry mouth are well-known indicators, doctors have highlighted several subtler signs that may signal the body needs more fluids.
Dr Naveed Asif, a GP at The London General Practice, said most people are probably mildly dehydrated most of the time, experiencing symptoms like dry mouth, lips and eyes. However, as dehydration worsens it can start to affect daily function and exacerbate existing medical conditions.
Among the surprising signs are restlessness or irritability, which Dr Hugh Coyne of Coyne Medical attributes to the brain being highly sensitive to hydration levels. Muscle cramping and tingling can also occur when electrolytes become too concentrated due to insufficient water intake, disrupting nerve and muscle function.
Headaches are another common symptom, caused by temporary shrinkage of brain tissue and reduced blood flow. Doctors also check skin turgor – the skin's elasticity – by pinching the back of the hand to see how quickly it springs back, though this can be less reliable in older adults who naturally lose skin elasticity. Fatigue, lethargy and an elevated heart rate are further early indicators.
Severe dehydration can lead to heat stroke, which has a high mortality rate. Dr Coyne stressed that symptoms such as confusion, agitation, slurred speech or loss of consciousness require emergency medical help. Certain groups, including infants and older people, should seek help at a lower threshold.
To prevent dehydration, experts advise drinking water regularly during hot weather, even before feeling thirsty, and paying attention to these less obvious signs to avoid serious illness.
