Dehydration
Peer reviewed by Dr Adrian Bonsall, MBBS
Meets Patient’s editorial guidelines
- DownloadDownload
- Share
In this series:Nausea and vomitingNausea medicine
This page has been archived.
It has not been reviewed recently and is not up to date. External links and references may no longer work.
Although dehydration can be mild and just needs you to drink extra fluids, it can also be very severe and life-threatening.
In this article:
Continue reading below
What is dehydration?
Dehydration means your body does not have enough fluid. This may be because you haven't drunk enough fluid to replace the fluids you have lost, such as when sweating or in your wee (urine). If dehydration isn't treated it can get worse and become a serious problem.
What are the causes of dehydration?
The causes include:
Not drinking enough fluids.
Being exposed to the sun in hot weather for long periods ('sunstroke').
Drinking too much alcohol.
Taking certain medicines called diuretics that reduce the amount of fluid in your body.
Babies, young children, the elderly and people with diabetes are at increased risk of dehydration.
Continue reading below
Signs and symptoms of dehydration
The symptoms include:
Feeling thirsty.
Dark yellow and strong-smelling wee (urine).
Feeling dizzy or light-headed.
Feeling very tired.
Dry mouth, lips and eyes.
Weeing less urine and less often.
However the symptoms and signs vary depending on age and the severity of dehydration.
Signs in adults
Thirst.
Dry or sticky mouth.
Not peeing very much.
Dark yellow pee.
Dry, cool skin.
Headache.
Muscle cramps.
Signs of severe dehydration
Not peeing, or having very dark yellow pee.
Very dry skin.
Feeling dizzy.
Rapid heartbeat.
Rapid breathing.
Sunken eyes.
Sleepiness, lack of energy, confusion or irritability.
Fainting.
Severe dehydration is a medical emergency and needs immediate treatment.
What are the treatments for dehydration?
Drink lots of fluids. If it's difficult to drink or you keep being sick (vomiting) then keep taking small sips of fluid and gradually drink more if you can.
If you're being sick or have diarrhoea and are losing too much fluid, you need to put back the sugar, salts and minerals that your body has lost. Your pharmacist can recommend oral rehydration powder sachets.
Speak with your doctor or nurse for advice if your symptoms don't improve or you have any concerns. Call 111 (in the UK) if you can't speak to your GP or don't know what to do next.
Call 999 (in the UK) or go to Accident and Emergency (A&E) if you have any signs of severe lack of fluid in the body (dehydration), such as:
Feeling very weak and tired.
Feeling confused or disorientated.
Dizziness.
Not having passed wee (urine) for eight hours.
Your pulse feeling weak and rapid.
Continue reading below
Babies and young children with dehydration
It's quite common for young children to become lacking in fluid (dehydrated). It is often mild but can be serious if it's not dealt with quickly. Babies and young children need plenty of fluids to avoid dehydration.
Signs of dehydration in babies, infants, toddlers and young children
The signs of dehydration include:
Dry mouth and tongue
No tears when crying
Dry nappies for over 3 hours
Sunken eyes and cheeks
Sunken soft spot on the top of the skull (fontanelle) in babies
Sleepiness, lack of energy, or irritability
Treatment of dehydration in babies and young children
You should continue breastfeeding or using formula. Give smaller quantities of milk more often than usual. Don't make formula weaker by diluting it with water.
Give small children their usual diet.
Give frequent small sips of extra water.
Use rehydration powder sachets, if available, to replace lost sugars, salts and minerals, as well as the fluid lost.
Avoid fruit juice or fizzy drinks because they can make diarrhoea or sickness (vomiting) worse.
Contact your doctor urgently or call an ambulance if your child displays any of the following signs or symptoms of dehydration:
Seems drowsy.
Is breathing fast.
Has a dry mouth.
Has dark-yellow wee.
Has cold and blotchy-looking hands and feet.
Further reading and references
- Diarrhoea and vomiting in children under 5; NICE Clinical Guideline (April 2009)
- Colletti JE, Brown KM, Sharieff GQ, et al; The management of children with gastroenteritis and dehydration in the emergency department. J Emerg Med. 2010 Jun;38(5):686-98. doi: 10.1016/j.jemermed.2008.06.015. Epub 2009 Apr 5.
- Hartling L, Bellemare S, Wiebe N, et al; Oral versus intravenous rehydration for treating dehydration due to gastroenteritis in children. Cochrane Database Syst Rev. 2006 Jul 19;(3):CD004390.
- Gastroenteritis; NICE CKS, March 2019 (UK access only)
Article history
The information on this page is written and peer reviewed by qualified clinicians.
Latest version
Are you protected against flu?
See if you are eligible for a free NHS flu jab today.
Feeling unwell?
Assess your symptoms online for free