Dehydration - 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 the main cause of heat exhaustion.

You should be able to reverse dehydration at this stage by drinking more fluids, without medical attention.

If dehydration is ongoing (chronic), it can affect your kidney function and cause kidney stones to develop. It can also lead to:

liver, joint and muscle damage
cholesterol problems
constipation

When to see your GP

See your GP if your symptoms continue despite drinking fluids, or if you suspect that your baby or toddler is dehydrated.

You should also contact your GP if your baby has passed six or more diarrhoeal stools in the past 24 hours, or if they have vomited three times or more in the past 24 hours.

If dehydration is suspected, you may be given a blood test or a urine test to check the balance of salts (sodium and potassium) in your body.

Severe dehydration

If dehydration is left untreated it can become severe.

Severe dehydration is a medical emergency and requires immediate medical attention.

Contact your GP or out-of-hours service straight away if you have any of the following symptoms:

feeling tired (lethargic) or confused
dry mouth and eyes that do not produce tears
not passing urine for eight hours
dry skin that sags slowly into position when pinched up
rapid heartbeat
blood in your stools (faeces) or vomit
low blood pressure (hypotension)
irritability
sunken eyes
a weak pulse
cool hands and feet
fits (seizures)
a low level of consciousness

If severe dehydration is not treated immediately, it can lead to complications. You can even die from severe dehydration because the blood stops circulating.

This level of dehydration needs hospital treatment and you will be put on a drip to restore the substantial loss of fluids.