How much should we drink?
According to NHS Choices, many studies have tried to establish a recommended daily intake of fluid, but it can vary depending on the individual and on factors such as age, climate and physical activity.
Some studies in the UK suggest that adults should drink 1.2 litres (6-8 glasses of water) per day to replace lost fluids and prevent dehydration.
A good general recommendation is to drink enough fluid so that you're not thirsty for long periods of time, and to steadily increase your intake during exercise or hot weather.
You should also drink fluid if you're having symptoms of dehydration, such as feeling thirsty and lightheaded, passing dark-coloured urine or not passing urine within six hours. It's also important to replace fluid lost after an episode of diarrhoea in order to prevent dehydration.
There are two types of dehydration:
isotonic dehydration – water and salt are lost in the same proportion as the water and salt present in the fluid surrounding your cells; this is the type of dehydration that's most often caused by diarrhoea
hypernatraemic dehydration usually affects infants or children; 'hypernatraemic' means high levels of salt in the blood, so hypernatraemic dehydration is where a child loses relatively more water than salt – for example, when they have watery diarrhoea or excessive vomiting.
What to do
If you're dehydrated, drink plenty of fluids. This can be water, semi-skimmed milk and diluted squash or fruit juice, but it's best to avoid fizzy drinks or caffeine if possible. If you're finding it hard to keep water down because you're vomiting or have diarrhoea, try drinking small amounts more frequently (perhaps using a teaspoon or syringe for an infant or child).
If you or your child are dehydrated due to watery diarrhoea or excessive vomiting (hypernatraemic dehydration), try not to drink only water as it's likely to further dilute the minerals in the body and make the problem worse. Try drinking diluted juice, squash or a rehydration solution (available from pharmacies).
If left untreated, severe dehydration can be serious and cause fits (seizures), brain damage and death.
When should I see my GP?
You should visit your GP if your symptoms continue, despite drinking plenty of fluids or if you suspect that your baby or toddler is dehydrated.
If your doctor suspects dehydration, you may be given a blood test or a urine test to check the balance of salts (sodium and potassium) in your body.
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 don't 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)
Also contact your GP if you or your child has diarrhoea that lasts longer than five days, or vomiting that lasts more than 24 hours in adults or 12 hours in a child.
If you suspect that someone is severely dehydrated, you should seek medical attention immediately. They may need to be admitted to hospital for treatment. In particular, babies, infants and elderly people will need urgent treatment if they become dehydrated.
Source: NHS Choices
Last reviewed: 24/08/2011
Next review due: 24/08/2013