Dehydration happens when you haven’t got enough fluids in your body. If severe, dehydration can cause serious problems. If you think you or someone with you is severely dehydrated, get them to hospital.
What is dehydration?
You are dehydrated if your body doesn't have enough water to keep it working properly. It can happen when your body loses too much fluid, such as from excessive sweating.
What causes dehydration?
People can get dehydrated:
- after strenuous exercise, especially in hot weather
- after severe vomiting or diarrhoea
- with a fever
- after drinking too much alcohol
- while taking certain medicines such as diuretics
- as a complication of diabetes
- if they don’t drink enough water
Anyone may become dehydrated, but babies, young children, older adults and people with long-term illnesses are at most risk.
Dehydration signs and symptoms
If you have mild to moderate dehydration, you might:
- be thirsty
- have a dry mouth, lips and tongue
- have a headache
- have dark urine, and not so much of it
- be dizzy or light-headed, particularly when standing up
If you have severe dehydration, you might:
- be extremely thirsty
- have a very dry mouth
- be breathing fast
- have a fast heart rate and a low blood pressure
- have a fever
- have little or no urine
- be irritable, drowsy or confused
Babies who are severely dehydrated have a sunken fontanel, the soft spot on top of a baby’s head.
Severe dehydration is a serious problem, especially in babies and young children.
Mild dehydration can be fixed by drinking more fluids. The simplest approach is to put 6 teaspoons of sugar with half a teaspoon of salt in one litre of boiled water. Here are instructions. You can also buy premade solutions from the pharmacy. Avoid alcohol and caffeine, as they can make you more dehydrated.
Severe dehydration needs immediate medical treatment, usually in hospital where fluids are given through an intravenous drip.
Make sure you drink enough water each day, and have extra to replace any fluid lost during hot weather, illness or exercise.
Drink lots of fluids or oral rehydration solution to treat mild to moderate dehydration. See your doctor or go to a hospital emergency room if you, your baby, child or elderly relative is severely dehydrated.
Last reviewed: January 2018