Dehydration occurs when your body loses more fluid than you take in.
When the normal water content of your body is reduced, it upsets the balance of minerals (salts and sugar) in your body, which affects the way it functions.
Water makes up over two-thirds of the healthy human body. It lubricates the joints and eyes, aids digestion, flushes out waste and toxins, and keeps the skin healthy.
What causes Dehydration?
Dehydration is usually caused by not drinking enough fluid to replace what we lose. The climate, the amount of physical exercise you are doing (particularly in hot weather) and your diet can contribute to dehydration.
You can also become dehydrated as a result of an illness, such as persistent vomiting and diarrhoea, or sweating from a fever.
Symptoms of dehydration
Dehydration can be mild, moderate or severe, depending on how much of your body weight is lost through fluids.
Two early signs of dehydration are thirst and dark-coloured urine. This is the body's way of trying to increase water intake and decrease water loss.
Other symptoms may include:
- dizziness or light-headedness
- headache
- tiredness
- dry mouth, lips and eyes
- passing small amounts of urine infrequently (less than three or four times a day)
Dehydration can also lead to a loss of strength and stamina. It's a main cause of heat exhaustion.
You should be able to reverse dehydration at this stage by drinking more fluids.
If dehydration is ongoing (chronic), it can affect your kidney function and increase the risk of kidney stones. It can also lead to muscle damage and constipation.
Who is at risk from dehydration?
Anyone can become dehydrated, but certain groups are particularly at risk. These include:
- babies and infants – they have a low body weight and are sensitive to even small amounts of fluid loss
- older people – they may be less aware that they are becoming dehydrated and need to keep drinking fluids
- people with a long-term health condition – such as diabetes
- athletes – they can lose a large amount of body fluid through sweat when exercising for long periods
