As temperatures soar across the UK, health experts are emphasising the critical importance of staying hydrated. Dehydration is a common concern during heatwaves, and it can manifest through surprising symptoms beyond the well-known signs of thirst and dry mouth.
Understanding Dehydration
Dr Naveed Asif, a GP at The London General Practice, explains that dehydration ranges from mild to severe. "Most of us are probably mildly dehydrated the majority of the time and experience things like a dry mouth, dry lips and dry eyes," he says. "Once it goes into moderate, it begins to impact you more, and severe dehydration can make you significantly unwell." Pre-existing medical conditions can also be exacerbated by dehydration.
Six Surprising Signs of Dehydration
1. Mood Changes
Dr Hugh Coyne, co-founder of Coyne Medical, notes that dehydration can cause restlessness or irritability. "The brain is sensitive to hydration levels. People might feel more tense and agitated, especially on hot mornings, until they drink water."
2. Muscle Cramps
Electrolyte imbalances from dehydration can trigger muscle cramps and tingling. Dr Asif explains: "Nerves controlling muscles become less efficient, causing muscles to seize up."
3. Headaches
Even mild dehydration can cause headaches. "When total body water drops, the brain dehydrates slightly, leading to transient shrinkage and tension on the meninges, along with decreased blood flow and increased pain sensitivity," says Dr Coyne.
4. Changes in Skin Elasticity
Skin turgor—the skin's ability to bounce back after being pinched—can indicate dehydration. In well-hydrated skin, it snaps back quickly; in dehydrated skin, it takes longer. This sign is less obvious in older adults due to natural loss of elasticity.
5. Fatigue
"Fatigue, tiredness and lethargy are common early signs of dehydration," says Dr Coyne. "That feeling of needing to sit down may indicate inadequate hydration."
6. Increased Heart Rate
Dehydration can elevate heart rate as the body tries to maintain blood pressure and organ perfusion. Dr Asif adds that stress hormones like adrenaline and cortisol are released to speed up the heart and deliver vital fluids to muscles and organs.
Importance of Addressing Dehydration
If left untreated, dehydration can lead to severe conditions like heat stroke, which has high mortality rates. Dr Coyne stresses the importance of prevention and early intervention. Altered mental status, confusion, agitation, slurred speech, or loss of consciousness require emergency help, as these are characteristic of heat stroke. Higher risk groups, such as infants and older adults, should seek medical attention at a lower threshold.
Tips to Stay Hydrated
Don't Wait Until You're Thirsty
Thirst can be an unreliable indicator, especially in older adults. Sip water throughout the day, and consider taking 10 sips at once regularly to maintain hydration.
Look After Your Skin
Apply moisturiser to help keep skin hydrated.
Consider Electrolytes When Exercising
For exercise under an hour, water is sufficient. For longer sessions, a carbohydrate-electrolyte sports drink is recommended.
Stay Cool
Keep blinds down, use air conditioning, fans, and misting to create a cool environment.
Monitor Your Urine Colour
Aim for light yellow or almost clear urine. Darker urine indicates a need for more fluids.
