Dehydration is a lack of water in the body, which disturbs the careful balance of minerals. This can be caused from many things, such as not drinking enough water, sweating, vomiting or diarrhoea.
Left unchecked, dehydration can be serious so it is important you know the symptoms and signs so you can take action quickly.
What are the most common symptoms of dehydration?
The most common signs that you could be suffering from dehydration are:
- Thirst (a dry or sticky mouth). This may seem obvious, but when you’re thirsty, it’s a sign that you’re already starting to dehydrate
- Not urinating much or darker yellow urine
- Dry, cool, shrivelled skin, or sunken eyes
- Tiredness, irritability or confusion
- Dizziness or light-headedness
- Rapid heartbeat and/or breathing.
What causes dehydration?
Dehydration is often caused by simply not drinking enough water, sweating, vomiting or diarrhoea.
Certain people are more vulnerable to dehydration, and a number of factors contribute towards this, including:
- Body size
Children and infants are more prone to dehydration.
As you get older your body isn’t as efficient at conserving water and responding to changes in temperature. You also become less aware of thirst. Elderly people may simply forget to eat or drink entirely and may need to be reminded.
Certain medications, such as diuretics and some blood pressure medicines, can increase your risk of dehydration because they make you urinate or sweat more than normal.
People with diabetes, kidney disease, dementia and heart failure are particularly vulnerable and should pay deliberate attention to staying hydrated. It’s especially important to drink more fluids when you have a fever or diarrhoea.
The longer you exercise and the more intensive the exercise the more water you will need to replace that lost by sweating.
- High altitude
High altitude (more than 2,500 meters) affects hydration because you have to breathe faster to maintain adequate oxygen levels in your blood. The faster you breathe, the more water vapour you exhale.
When it's hot and humid, you sweat more. Without enough fluids, you can’t sweat enough to cool your body. The risks can vary from mild heat cramps or exhaustion, to potentially life-threatening heatstroke.
How can you prevent dehydration?
Drinking water regularly through the day is the best way to prevent dehydration. All drinks count towards your daily fluid intake, although you should try to avoid alcohol and caffeine as both are diuretics (you’ll be going to the toilet more and losing water from your body).
Water doesn’t just have to come from the tap. There are lots of ways to make sure your body keeps topped up, as shown in our handy infographic.
Dehydration – NHS factsheet
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