Dehydration: signs and what to do
In short: early dehydration usually causes thirst, a dry mouth, less urine and darker urine. Sipping fluids usually helps. Confusion, fainting, a racing heart or not urinating are signs to get medical help right away.
What dehydration is
Dehydration happens when your body loses more water and fluids than it takes in. Common causes are:
- vomiting or diarrhoea
- fever
- heavy sweating, for example in hot weather or during exercise
- not drinking enough, for example when you're unwell or busy
- some medicines, such as water tablets (diuretics)
Signs of mild to moderate dehydration
- Feeling thirsty
- Dry or sticky mouth
- Peeing less often, or dark yellow urine
- Dry, cool skin
- Headache
- Muscle cramps
- In babies: fewer wet nappies (diapers) than usual
What to do
- Drink fluids little and often. Water is usually enough for mild dehydration.
- If you have vomiting or diarrhoea, an oral rehydration solution from a pharmacy replaces lost salts as well as water. Follow the instructions on the packet.
- Rest somewhere cool, out of the sun.
- For babies and young children, keep offering breast milk, formula or fluids, and get advice early (see below).
Who is most at risk
Babies and young children, older adults, and people with long-term conditions such as diabetes or kidney disease can become dehydrated more quickly and should get advice sooner.
When to get medical help
Call 911 or your local emergency number if someone:
- faints, or becomes confused, very drowsy or hard to wake
- has a seizure
- has a very fast heartbeat or fast breathing
- hasn't passed any urine
- shows signs of heatstroke, such as hot skin, confusion or collapse after being in the heat
Contact a doctor or other health professional if:
- a baby or young child shows any signs of dehydration, or a baby has had no wet nappy for 3 hours or more
- vomiting or diarrhoea means you can't keep fluids down
- there is a high fever, or symptoms don't improve or get worse
Sources
- MedlinePlus (U.S. National Library of Medicine): Dehydration
- MedlinePlus: Dehydration (health topic)
- MedlinePlus: Diarrhea