Dehydration
Dehydration is when your body loses more fluid than you take in. It can be serious if it isn’t treated.
Drinking fluids (such as water, diluted squash or fruit juice) regularly can prevent dehydration.
Symptoms of dehydration
Symptoms of dehydration include:
- feeling thirsty
- having dark yellow, strong-smelling pee (urine)
- peeing less often than usual (less than 3 or 4 times a day)
- feeling dizzy or lightheaded
- headache
- feeling tired
- a dry mouth, lips and eyes
- sunken eyes
A baby may be dehydrated if they have:
- a sunken soft spot (fontanelle) on their head
- sunken eyes
- few or no tears when they cry
- a dry mouth
- fewer wet nappies
- dark yellow pee
- drowsiness or are irritable
- fast breathing
- cold and blotchy-looking hands and feet
When to get medical advice
Urgent advice: Speak to your GP practice urgently if:
- you’re extremely thirsty
- you’re feeling unusually tired (or your child seems drowsy)
- you’re confused and disorientated
- you feel dizzy when you stand up and it does not go away after a few seconds
- you have dark yellow pee or you’re peeing less than normal (or your baby has fewer wet nappies)
- you or your child are breathing quickly or has a fast heart rate
- your baby or child has few or no tears when they cry
- your baby has a soft spot on their head that sinks inwards (sunken fontanelle)
- your baby has vomited 3 times or more in the past 24 hours
- your child has had 6 or more episodes of diarrhoea in the past 24 hours
- your symptoms continue even after drinking fluids
- you think your baby or toddler is dehydrated
If your GP practice is closed, phone 111.
Diagnosing dehydration
If your GP suspects dehydration, you may have a blood test or a urine test to check the balance of salts in your body.
What causes dehydration?
Dehydration is caused by not drinking enough fluid or by losing more fluid than you take in.
Fluid is lost through sweat, vomit, pee or diarrhoea.
Causes of dehydration include:
- illness – for example gastroenteritis, where you lose fluid through diarrhoea and vomiting
- sweating too much – for example due to a fever, exercise, or manual work in high temperatures
- drinking too much alcohol because it makes you pee more – a hangover headache is a sign you’re dehydrated
- diabetes – high levels of glucose in your blood makes you pee more
Who is at risk of dehydration?
Anyone can become dehydrated but those more at risk are:
- babies and infants – their low body weight makes them sensitive to even small amounts of fluid loss
- older people – they may be less aware they’re becoming dehydrated and need to drink fluids
- people with a long-term health condition – such as diabetes or alcoholism
- athletes – they can lose a large amount of body fluid through sweat when exercising for long periods
Overhydration (hyponatremia)
It’s possible to become overhydrated while exercising. Overhydration is caused by low salt levels in the blood. It can occur if you drink too much water over a short period of time.
It sometimes affects athletes if salt is lost through sweat and diluted by drinking large amounts of water.
Symptoms of overhydration include feeling sick, vomiting and headache. In serious cases, the brain can swell, causing confusion, seizures, coma and, in rare cases, death.
If you’re worried that you may be overhydrated, seek medical advice.
Treatment for dehydration
If you’re dehydrated, drink plenty of fluids such as water, diluted squash or fruit juice. These are better than tea, coffee or fizzy drinks.
If you’re finding it difficult to keep water down because you’re vomiting, try drinking small amounts more often.
Oral rehydration solutions
When you’re dehydrated, you lose sugar and salts, as well as water. Oral rehydration solutions can help treat this. These are powders that you mix with water and then drink. They contain a mixture of potassium and sodium salts, as well as glucose or starch.
Ask your pharmacist or GP for advice about the right rehydration solution for you or your child.
Treatment for babies
Give your baby plenty of liquids, such as breastmilk or formula. It can be better to give them smaller amounts of fluid more often.
Don’t dilute your baby’s formula (if you use it). Babies who are formula-fed and those on solids can be given extra water.
Avoid giving your baby fruit juice, particularly if they have diarrhoea and vomiting, because it can make it worse.
Giving your baby regular sips (a few times an hour) of oral rehydration solution as well as their usual feed (breastmilk, formula milk and water) will help to replace lost fluids, salts and sugars. Ask your pharmacist for advice.
Treatment for infants and children
Infants and children who are dehydrated shouldn’t only be given water. It can dilute the already low level of minerals in their body and make the problem worse. Instead, they should have diluted squash or oral rehydration solution. Ask your pharmacist for advice.
If your child is finding it difficult to keep fluid down because of vomiting, take small amounts more often. You may find it easier to use a spoon or a syringe into their mouth to give your child small amounts of fluid.
Treatment for severe dehydration
If severe dehydration is not treated immediately, it can lead to serious complications. Severe dehydration needs hospital treatment. You’ll be put on a drip to quickly replace fluid in your body.