How can you tell if you’re dehydrated & how you can avoid it? We give you the rundown on rehydrating your body

Water makes up over-two thirds of a healthy human body, and helps our body carry out many of its daily functions – from aiding digestion and cushioning joints to helping flush out our waste and keeping our skin healthy.

But when the normal water content of our bodies is reduced, this can upset the balance of minerals (salts and sugar) and affects our body’s ability to function properly.

What causes dehydration?

Dehydration occurs when your body loses more fluids than it takes in. You might find this happens easily if you sweat a lot after exercise, you’ve drunk too much alcohol or have been in the sun for too long (which can lead to heatstroke). Dehydration might also happen more easily if you:

• Have diabetes

• Have been sick or have diarrhoea

• Have a high temperature

• Take medicines that make you pee more (diuretics)

What are the symptoms of dehydration?

Symptoms of dehydration include:

• Feeling thirsty

• Dark yellow, strong-smelling pee

• Peeing less than usual

• Feeling lightheaded or dizzy

• Feeling tired

• A dry mouth, lips and tongue

• Sunken eyes

Who is most at risk from dehydration?

Anyone can become dehydrated, but certain groups are particularly at risk. These include:

Babies & infants

As they have a low body weight, babies and children are sensitive to even a small amount of fluid loss.

Signs of dehydration in babies also include:

• Sunken eyes

• A sunken spot (fontanelle) on top of their head

• Few or no tears when they cry

• Not having many wet nappies during the day

• Being drowsy or irritable

Older people

Some older adults may be less aware that they’re becoming dehydrated. If you help care for somebody, make sure they drink fluids at meal times and offer them food with a high water content, such as fruits like melon.

People with long-term health conditions

This includes conditions like diabetes or alcoholism.


Athletes can lose a large amount of fluid through sweat when they exercise for long periods of time.

What’s the treatment for dehydration?

If you notice any symptoms of dehydration, start by drinking plenty of fluids – that might be water or diluted squash.

Many people wonder if tea or coffee make you dehydrated, but drinking them does count towards your daily fluid intake. The Eatwell Guide recommends people should aim for six to eight cups or glasses of fluid a day. However, drinking water is much more effective at hydrating you than large amounts of tea or coffee that contain caffeine. Herbal teas don’t contain high levels of caffeine so may be more effective at hydrating.

Rehydrating with fizzy drinks isn’t recommended, as they can contain a lot of sugar – more than you need to replenish your minerals – and can be more difficult to drink in large amounts.

If you feel sick or have been sick and you’re finding it hard to drink, start with small sips and gradually drink more. 

A pharmacist might be able to help with dehydration, too. If you’re being sick or have diarrhoea, losing this much fluid means you’ll need to put back the sugar, salts and minerals your body has lost. If this is the case, your pharmacist may recommend oral rehydration solutions – these are usually powders that are mixed into water.

Babies or small children who are dehydrated shouldn’t be given large amounts of water alone to replace their fluids, as this can dilute the level of minerals in their body too much. Instead, they should be given diluted squash or a rehydration solution recommended by a pharmacist or a GP for those under the age of 1 year.

How to prevent dehydration

Drinking regularly helps reduce your risk of dehydration. You should be drinking enough throughout the day so your pee is a pale clear colour – aim for six to eight glasses of fluid a day.

Try to drink extra fluids when you know there is a higher risk of becoming dehydrated – for example if you’re being sick, sweating, or you have diarrhoea.

When to seek medical help

See your GP if your symptoms of dehydration continue despite drinking plenty of fluids, or if you think your baby or toddler is dehydrated.

Ask for an urgent GP appointment or call NHS 111 if:

• You’re feeling unusually tired (or your child seems drowsy)

• You’re confused and disorientated

• You feel dizzy when you stand up and it doesn’t go away

• You have dark yellow pee or you’re peeing less than normal (or your baby has fewer wet nappies)

• You or your child are breathing quickly or has a fast heart rate

• Your baby or child has no tears when they cry

• Your baby has a soft spot on their head that sinks inwards (sunken fontanelle)

These can be signs of severe dehydration that will need urgent treatment.