Is my baby dehydrated? Signs, symptoms and what to do

Dehydration happens when the body loses more fluids than it takes in. If a baby gets dehydrated and is left without treatment, it can become serious¹.

Babies and children do have a higher risk of dehydration due to their low body weight, meaning they’re sensitive to even minor levels of fluid loss². However, the important thing is knowing what to do if they become dehydrated. Most of the time, you can help them at home.

This guide will cover what causes a dehydrated baby or toddler, symptoms and signs of dehydration in babies, treatment options, and how you can try to prevent dehydration in children in the first place.

What causes dehydration in babies?

There are various causes for dehydration in young children, and these can vary based on whether they’re newborns, older babies or toddlers.

Newborns

When newborns first learn how to drink milk, they may have hiccups and experience some trouble swallowing and digesting it³. Issues latching on and getting milk are also common – meaning some newborns also lose weight in the first week after they’re born³.

With this in mind, dehydration in newborns can be caused by:

• Low breast milk supply. If you’re not producing enough milk, your baby may not receive enough hydration and nutrients. Try to monitor your milk supply to make sure your little one is getting everything they need⁴.

• Baby spitting up or vomiting. The more your little one is sick, the more likely they are to become dehydrated, due to the loss of fluids and salt ⁴.

• Breast milk doesn’t have the right balance of salts and water. This is very rare cause of newborn baby dehydration ³, but can happen.

• Baby not latching on. If your baby isn’t latching on properly, you may need to try different ways to give them milk ³.

Babies and Toddlers

It’s important to remember that your little one is more at risk of becoming dehydrated when they’re unwell. Dehydration in toddlers can result from stomach viruses, food intolerances and allergies – or even the flu³.

Other risk factors for dehydration include:

• Vomiting or diarrhoea ⁴

• Overheating, or sweating a lot. Be mindful of clothing that’s too warm or made from a non-breathable fabric ⁴.

• Fever³. Sweating from a fever can lead to dehydration⁴.

• A temperature of 38 degrees Celsius, or higher⁵.

• Being out in hot weather. Try to always shield your baby from the sun’s rays where possible. You should keep them in the shade and as cool as you can⁴.

• Not having enough fluids ⁵

• Having a chest infection. This makes it more challenging for them to drink or feed⁵.

The signs of dehydration in babies

Baby dehydration symptoms can vary depending on the level of water loss. They may also be quite different for newborns, babies and toddlers³

Newborns

You may notice the following signs of dehydration in newborns³:

• When they cry, they have fewer tears than normal, or none at all.

• They may have sunken eyes.

• They may be particularly fussy³, drowsy or irritable².

• You notice they’re sleeping too much (or more than usual).

• They may have cold or even discoloured hands and feet.

• You may notice they have particularly wrinkly skin.

• They may have a sunken spot on top of their head³. This is called a ‘fontanelle’¹.

Babies and Toddlers

Keep an eye out for these signs of dehydration in babies and toddlers:

• Your little one may seem out of character and not want to play³.

• You may notice fewer wet nappies to change¹, compared to normal. For infants, this may be fewer than six per day⁶, but you will know what’s typical for your child.

• As with newborns, your child may have sunken eyes, fewer tears when they cry and cold hands³.

• They may have a dry mouth³, lips or tongue¹.

• They may be acting cranky or feeling tired – more than usual³.

• You may notice fast breathing and/or a fast heart rate³.

• Your child may experience a change in bowel movements. They may have loose stool if the dehydration is a result of diarrhoea, or have fewer movements if it’s caused by vomiting or a lack of fluid⁶.

In severe cases, your infant or child may also be⁶:

• Very fussy

• Excessively sleepy

• Only urinating a couple of times a day⁶.

How to treat dehydration in babies

The right way to treat a dehydrated baby depends on the cause of dehydration. The best course of action will also vary according to how old your little one is³.

If your young baby is showing signs of being dehydrated, these are a few treatment options to consider:

• It’s important that your little one is consuming lots of fluid, like breastmilk or formula. But don’t be tempted to dilute it². It’s best to provide little amounts of fluid regularly². Babies that are fed on formula or solid food can have extra water².

• Consult with a pharmacist for advice on oral rehydration solutions alongside your child’s normal feed. It’s possible that this could help to give your baby back any lost salts or sugars².

• Don’t give them fruit juice. This is particularly important if they have loose stool or are vomiting¹.

However, if an infant or older child is dehydrated, there’s a slightly different approach. You shouldn’t only give them water, as it may dilute the already low level of minerals in their body. Instead, provide them with diluted squash or oral rehydration solution. Again, check with your pharmacist or GP for advice².

If you’re concerned that they are overly-hot as well, visit our guide on high temperature.

Calpol® products can help to reduce and soothe your baby’s fever. Depending on their age, you could try:

• CALPOL® SixPlus Fastmelts.Your child can take these dissolve-in-the-mouth tablets without water, for on-the-go pain relief. Suitable for children six years and older.

• CALPOL® Infant Sugar Free Suspension. Suitable for babies and children from two months to six years. As long as they’re not premature and weigh more than 4kg, this sugar-free suspension gets to work on their fever in just 15 minutes.

• CALPOL® SIXPlusTM Oral Suspension Paracetamol for Children. Appropriate for children six years and older. This suspension is over twice the strength of our infant paracetamol suspension, for effective and soothing fever relief.

Preventing dehydration in babies

Nobody wants to see their little one feeling poorly. And you can’t always stop your baby getting a little dehydrated. But there are ways you can try to reduce the chances of it happening, and stop it from getting too serious³.

• Regular feeding is essential – your newborn only has a tiny stomach that slowly gets bigger³. A newborn typically needs around nine feedings each 24 hours³, so your baby will need to be consuming enough breastmilk or formula – remember that little and often is best².

• It’s important that your little one drinks fluids regularly. Kids under five years old need lots of fluids to prevent them from getting dehydrated ¹.

• Keeping track of how often and how much your baby goes to the toilet is a useful indication of how much fluid they’re consuming³. It’s a good idea to monitor how many times a day you’re changing their nappy³.

Watery or explosive stools could be a sign they have diarrhoea, and they may be losing fluids. By contrast, dry, hard stools could indicate they’re dehydrated³.

When to seek help for a dehydrated baby

Babies and toddlers can become dehydrated more quickly due to having such low body weight³. Things can become quite serious for babies and toddlers if their dehydration symptoms are not addressed too – and severe dehydration can happen quite quickly³.

You should seek medical attention if your baby:

• Has a rectal temperature of 38 degrees Celsius or above.

• Is projectile vomiting.

• Is not able to keep any milk down or take from a breast or bottle. This could indicate a health condition that’s preventing them from drinking the milk ³.

Serious cases of dehydration may need hospital treatments and the use of IVs. Your GP may also recommend an electrolyte solution to replace lost salts and nutrients³.

As mentioned above, dehydration can cause these symptoms:

• Drowsiness¹

• Fast breathing or fast heart rate¹

• Few or no tears when crying¹

• Fewer wet nappies¹

• A soft spot on their head that sinks inwards¹.

If your little one is experiencing any of these symptoms, you should call 111 or your doctor for an urgent appointment¹.

Dehydration in babies FAQs

Why is my baby drinking but there are no wet nappies?

If your baby is drinking but is not producing wet nappies, it could be a sign that they’re dehydrated¹.Symptoms of a dehydrated baby can also include acting drowsy and irritable, having sunken eyes, a soft spot on their head, and producing fewer or no tears at all when crying^1.

Can a fever cause dehydration?

Yes, a fever can cause dehydration in babies³. For example, a fever can cause your little one to lose fluids through sweating, which in turn can result in dehydration⁴. Certain CALPOL^® products can help to soothe symptoms of fever in children. Always consult packaging for correct dosage and age-appropriate treatment. You can also ask your GP or pharmacist for advice.

How to tell if my baby is dehydrated?

There are some telltale signs to look out for which could mean your baby is dehydrated. According to the NHS, your little one may have fewer wet nappies and less or no tears when they cry¹. They may also have sunken eyes, and a sunken spot called a ‘fontanelle’ on top of their head¹.