Dehydration: symptoms, treatment and when to get help

The NHS says symptoms of dehydration in adults and children include the following. NHS inform gives a guide for peeing: less often than usual, which it describes as fewer than 3 or 4 times a day.

• Feeling thirsty.

• Headache, and feeling light-headed or dizzy.

• Dark yellow, strong-smelling pee, or peeing less often than usual.

• Feeling tired.

• A dry mouth, lips and tongue (NHS inform also mentions dry eyes).

• Sunken eyes.

The NHS says signs of dehydration in a baby may include a sunken soft spot (fontanelle) on top of the head, sunken eyes, few or no tears when they cry, fewer wet nappies than usual, and being drowsy or irritable. NHS inform adds a dry mouth, dark yellow pee, fast breathing, and cold and blotchy-looking hands and feet.

The NHS says babies and children can become dehydrated more easily, and that children under the age of 5 and older adults should get plenty of fluids because they have an increased risk. NHS inform explains that babies and infants are sensitive to even small amounts of fluid loss because of their low body weight.

You should drink fluids if you have symptoms of dehydration, says the NHS. If you feel sick or have been sick, start with small sips and then gradually drink more. NHS inform suggests water, diluted squash or fruit juice, which it says are better than tea, coffee or fizzy drinks, and the NHS says to avoid caffeinated drinks and alcohol because both will dehydrate you.

If you are being sick or have diarrhoea and are losing too much fluid, you need to put back the sugar, salts and minerals your body has lost. The NHS says a pharmacist can recommend oral rehydration solutions, which are powders that you mix with water and then drink. NHS inform says they contain a mixture of potassium and sodium salts as well as glucose or starch.

Severe dehydration needs hospital treatment. NHS inform says that if it is not treated immediately it can lead to serious complications, and that you will be put on a drip to quickly replace fluid in your body.

NHS inform advises giving a baby plenty of liquids such as breastmilk or formula, in smaller amounts more often, and not diluting formula. Babies who are formula-fed or on solids can be given extra water. The NHS says that if a baby is under 6 months the water should be boiled and cooled first. Regular sips of oral rehydration solution, a few times an hour, replace lost fluids, salts and sugars. Ask a pharmacist for advice.

NHS inform says infants and children who are dehydrated should not only be given water, because 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. If a child cannot keep fluid down because of vomiting, give small amounts more often, using a spoon or a syringe into the mouth if that is easier.

The NHS says to avoid fruit juice or fizzy drinks for young children as they can make diarrhoea or vomiting worse, not to make formula weaker, to carry on breastfeeding or using formula, and to give small children their usual diet once dehydration has been treated.

Dehydration is when your body loses more fluid than you take in. NHS inform says it is caused by not drinking enough fluid or by losing more fluid than you take in, through sweat, vomit, pee or diarrhoea. It can be serious if it is not treated, but drinking fluids regularly can prevent it.

The opposite is possible too. NHS inform describes overhydration (hyponatremia) caused by low salt levels in the blood, which can occur if you drink too much water over a short period, sometimes in athletes. Symptoms include feeling sick, vomiting and headache, and in serious cases the brain can swell, causing confusion, seizures and coma. Seek medical advice if you are worried.

The NHS says dehydration can happen more easily if you have diabetes, have been sick or have diarrhoea, have been in the sun or a hot environment too long, have drunk too much alcohol, sweat a lot after exercising, have a high temperature, take medicines that make you pee more (diuretics), or rely on other people to get you drinks.

NHS inform lists those more at risk as babies and infants, older people (who may be less aware they are becoming dehydrated), people with a long-term health condition such as diabetes or alcoholism, and athletes who lose a large amount of fluid through sweat.

The sources reviewed do not give a set time for dehydration to resolve; it depends on how much fluid has been lost and whether the cause is still going on. The NHS says you should drink fluids if you have symptoms, and NHS inform says to contact your GP practice urgently if symptoms continue even after drinking fluids.

When dehydration comes from diarrhoea and vomiting, the NHS says diarrhoea usually stops within 5 to 7 days and vomiting usually stops in 1 or 2 days, in adults and children. Call 111 if diarrhoea lasts more than 7 days or vomiting more than 2 days, or if you or your child keep being sick and cannot keep fluid down.

The NHS says you may need to drink more fluids if you are pregnant or breastfeeding, as well as in a hot environment, if you are physically active for long periods, or if you are ill or recovering from illness.

Morning sickness is very common in early pregnancy and, the NHS says, usually clears up by weeks 16 to 20. There is a chance of developing a severe form called hyperemesis gravidarum, which can be serious because you may not get enough fluids in your body (dehydration) and may need specialist treatment, sometimes in hospital. The NHS suggests drinking plenty of fluids such as water, sipping them little and often.

Call your midwife, GP or 111 if you are vomiting and have very dark-coloured urine or have not had a pee in more than 8 hours, are unable to keep food or fluids down for 24 hours, feel very weak, dizzy or faint when standing up, have tummy pain, have a high temperature, vomit blood, or have lost weight.

These can be signs of serious dehydration that need urgent treatment. The NHS says to ask for an urgent GP appointment or get help from NHS 111 for the first group below, and to call 999 or go to A&E for the second. Do not drive yourself to A&E. Ask someone to drive you or call 999.

If your GP suspects dehydration, NHS inform says you may have a blood test or a urine test to check the balance of salts in your body. In most mild cases the symptoms and the circumstances, such as a stomach bug or hot weather, are what point to the diagnosis.

Drinking fluids regularly can reduce the risk. The NHS says water or diluted sugar-free squash are good choices, and you should drink enough during the day so that your pee is a pale colour. Drink more when there is a higher risk, for example if you are being sick, sweating due to hot weather or exercise, or have diarrhoea.

If you care for someone, the NHS says they may not have a sense of how much they are drinking. You can help by making sure they drink at mealtimes, making drinking a social thing, offering foods with a high water content such as soup, ice cream, jelly and fruits like melon, and making sure they have access to fluids at all times.

Most dehydration is managed at home or with advice from a pharmacist, who can recommend an oral rehydration solution. If symptoms do not settle or any urgent signs appear, the NHS route is the GP practice, NHS 111 (which can arrange a call from a nurse or doctor) and A&E or 999 for emergencies.

A private GP is an alternative route to assessment and blood tests, but severe dehydration needs hospital treatment, so do not wait for a private appointment if there are urgent signs.