Dehydration in Babies: Symptoms, Treatment and Prevention

As a parent, you want to do everything possible to keep your baby healthy. Even so, things like a fever, vomiting or a particularly hot day can lead to dehydration.

Learn about the signs and symptoms of dehydration in babies, toddlers and older children, how you can prevent dehydration to begin with and what to do if your baby does become dehydrated.

What Is Dehydration?

Our bodies need water and other fluids to function properly. Over the course of a day, it’s normal for your baby to lose and replenish water – sweating, crying, peeing and doing poos are all ways of losing water. That water is replaced when your little one feeds, eats or drinks.

Dehydration can occur if your baby or toddler loses more fluid than he or she takes in. This applies to adults and kids alike, but dehydration tends to happen more easily in babies and young children than in grown-ups.

Dehydration is usually easy to treat but can be serious if it isn’t dealt with immediately. This is why it’s important to recognise the signs and symptoms and get treatment as soon as possible.

Signs and Symptoms of Dehydration in Babies and Children

Signs of dehydration in your baby or toddler can include:

  • Dry mouth

  • Few or no tears when crying

  • Sunken eyes

  • Dark yellow wee, or no wee in the last 12 hours

  • More dry nappies than usual

  • Sunken fontanelle (the soft spot on your baby’s head)

  • Drowsiness

  • Fast breathing

  • Cold and blotchy hands and feet.

If your baby or child shows any of these signs of dehydration, call your doctor or health visitor immediately or visit your local A&E unit.

Dehydration Treatment

The treatment for dehydration aims to replace the missing fluids, minerals salts and sugars. The ways of doing this can vary from simply administering a rehydration solution to the replacement of fluids via an intravenous drip.

Precisely which treatment is needed depends on various factors, including your baby’s age and how severe the dehydration is.

This is why it’s essential to call your doctor or visit A&E if you notice signs of dehydration in your baby or toddler: Your child needs to be assessed so any urgent treatment can be given, if needed.

After this, based on your child’s age and an assessment of the symptoms, you may be advised to

  • keep breastfeeding or giving your baby formula (It may help to give smaller, but more frequent feeds.)

  • give small sips of extra water if your baby is on formula or has started on solid foods

  • give small sips of a rehydration solution (recommended by your doctor or a pharmacist), to replace the fluids, salts and sugars that your child needs

  • NOT give your child fizzy drinks or fruit juices, which can make vomiting or diarrhoea worse – if these symptoms of illness are what caused the dehydration in the first place.

What Causes Dehydration?

Dehydration can happen more easily when children have diarrhoea, vomiting or a fever, or during hot weather. Find out more about these causes of dehydration below.


An occasional loose stool is nothing to worry about, but sometimes your baby or toddler may get diarrhoea due to a tummy bug or other illness.

When diarrhoea strikes, important minerals and salts are also lost along with the water through your child's stools, and this can lead to dehydration.


Many illnesses, including stomach viruses or food poisoning, can cause vomiting, which in turn can lead to dehydration.

To prevent dehydration, it's important to ensure that your child is getting extra fluids. If your little one can’t keep the fluids down, call 111 or speak to your health visitor or doctor, who can advise on next steps.


A fever (a high temperature of 38 degrees Celsius or higher) is your child’s natural response to infection. However, it can also lead to dehydration by causing your child to lose fluids more quickly.

Hot Weather

Babies and young children can easily become dehydrated in hot weather. You may need to give more frequent feeds if you are exclusively breastfeeding.

If you are bottle-feeding your baby, you can usually give him or her small amounts of cooled boiled water after his or her regular feeds.

If your baby is already on solids, you may need to offer extra water with meals and snacks to keep your little one hydrated in hot weather.

Find out more about when your baby can start drinking water.

As well as making sure your child gets enough fluid during the warmer months, you should also protect him or her from the sun. Besides helping to prevent dehydration, this is important for preventing baby sunburn and other hot-weather conditions like heatstroke.

When to See a Doctor

Let your doctor or health visitor know straight away if you notice any signs or symptoms of dehydration in your baby, toddler or older child.

It’s also important to tell your health visitor or doctor if you think your child may not be getting enough fluids – for example, if he or she is vomiting and can’t keep fluids down, or isn’t feeding or drinking enough.

Preventing Dehydration

It’s important to make sure your baby gets the right amount of fluid at all times, but – to prevent dehydration – this is especially important when he or she has an illness that causes fever, diarrhoea, or vomiting.

If you’re worried that your child is losing too much fluid, ask your pharmacist to recommend an oral rehydration solution that is suitable for your child. This comes in the form of a sachet containing powder that can be mixed with water to drink. It helps to replace the sugar, salts and other minerals that may have been lost.

Preventing Dehydration in Hot Weather

If you are outside on a hot summer's day with your child, stay in the shade whenever possible and avoid direct sunlight – especially if your baby is less than 6 months old.

These steps can also help ensure your child is well-hydrated during hot weather:

  • If your baby is under 6 months old and you are exclusively breastfeeding, give extra feeds. If your baby gets his or her nourishment from formula and/or you have started introducing solid foods to his or her diet, you also can give extra sips of water.

  • After 6 months of age, your child will probably already be drinking sips of water at meals, although the main drink should still be breast milk or formula. Extra sips of water after meals or between meals can help keep your baby’s fluids topped up in hot weather.

  • After 12 months of age, in addition to your child’s main drink of water, giving breast milk, whole cow’s milk, and plenty of fruit and salad can help replenish lost fluids. Frozen lollies made from plain water or very diluted fruit juice are another refreshing way of helping your little one stay hydrated.

No matter the weather, here’s a rough idea of at least how much fluid your child needs per day. More may be needed in hot weather. Keep in mind, this will be topped up as there is water in foods like fruit, soups, and vegetables.

How Much Fluid Does Your Child Need in a Day?*

AgeHow many (approx. 150 ml) glasses?Total quantity
1-2 years6900 ml
3-4 years6-71000 ml
5-8 years81200


Signs of dehydration can include:

  • Dry mouth
  • Few or no tears when crying
  • Sunken eyes
  • Dark yellow wee, or no wee in the last 12 hours
  • Fewer wet nappies than usual
  • Sunken fontanelle (the soft spot on your baby’s head)
  • Drowsiness
  • Fast breathing
  • Cold, blotchy hands and feet.

Call your doctor or health visitor immediately or visit your local A&E unit if you notice any of these symptoms.

The Bottom Line

Now you know what to look for, you'll hopefully be able to recognise the signs of dehydration and get treatment straight away. If you are worried that your child may be dehydrated or not getting enough fluid, try not to panic: Dehydration in babies can be scary, but your health visitor or doctor will know what to do.

Of course, it’s safest to prevent your little one getting dehydrated in the first place, so make sure your baby is getting plenty of fluids – especially if he or she is ill or the weather’s hot.

How we wrote this article
The information in this article is based on the expert advice found in trusted medical and government sources, such as the National Health Service (NHS). You can find a full list of sources used for this article below. The content on this page should not replace professional medical advice. Always consult medical professionals for full diagnosis and treatment.

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