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Kids Health Info

Dehydration in babies and children

  • Key points

    • Dehydration is when the body loses more water than it takes in.
    • Young children and babies are most at risk of getting dehydrated.
    • Illnesses that cause vomiting and diarrhoea can lead to dehydration.
    • Make sure your child drinks enough fluids when they are sick, so they do not get dehydrated.
    • If your child is not drinking enough fluids and they seem to be getting sicker, you should take them to a doctor.

    What is dehydration?

    Dehydration is when the body loses more water or fluid than it takes in.

    Water is important for many bodily processes, such as maintaining a healthy temperature, digesting food, and balancing salt and nutrient levels. A lack of water makes it harder for the body to work properly.

    Babies and young children are most at risk of dehydration for a few reasons. They:

    • lose more fluids through their skin
    • cannot always get fluids for themselves and usually need other people to give them fluids
    • are more likely to catch illnesses that cause them to lose fluids through vomiting and diarrhoea, such as gastroenteritis (gastro)
    • are more likely to catch respiratory illnesses, which cause symptoms like sore throats that make them avoid eating and drinking
    • may not be able to tell you when they need more fluids.

    Children with long-term health conditions like heart and kidney problems, and those who take certain medicines (such as diuretics), are more likely to get dehydrated.

    Try to keep your child hydrated at all times, and pay close attention to how much they drink when they are unwell. Severe dehydration can be dangerous.

    Signs and symptoms of dehydration

    Mild dehydration

    If your child has mild dehydration, they may:

    • feel thirsty
    • urinate (pee) less than usual.

    Moderate dehydration

    If your child has moderate dehydration, they may:

    • feel thirsty
    • be less active and quieter than usual
    • have cool hands and feet
    • have a dry mouth, lips and tongue
    • urinate (pee) less often and have darker urine than usual.

    Severe dehydration

    If your child has severe dehydration, they may:

    • have cold hands and mottled (patchy, reddish-blue patterned) skin
    • seem lethargic (low energy) and very sleepy
    • have sunken eyes
    • urinate (pee) a lot less often and smaller amounts than usual, or not at all.

    Severe dehydration is serious and can worsen quickly. You must seek medical help fast.

    How to care for dehydration at home

    Addressing the cause of dehydration

    Dehydration is often a symptom of another illness. Viral infections are a very common cause.

    If your child has:

    • a sore throat, mouth pain, fever or aches and pains stopping them from drinking, pain-relief medicine like paracetamol or ibuprofen often helps.
    • a blocked or snotty nose that makes it harder for them to feed, consider using a nasal spray or nasal aspirator to suction out the mucous and clear the nose.
    • nausea or vomiting, speak to their doctor who may prescribe an anti-nausea medicine like ondansetron.

    Do not give your child medicines to slow down diarrhoea as they can have harmful side effects.

    Best fluids to treat dehydration

    Clear fluids are great for helping rehydrate, as the body absorbs them faster. They also taste better to most sick children. However, if your child is drinking other fluids like milk, keep giving it to them.

    The best clear fluids for most children with dehydration are water, apple juice mixed with water and oral rehydration solutions – either liquids or icy poles. Oral rehydration solutions give the body fluids and salts; you can buy them at supermarkets and pharmacies. They are the best for treating dehydration, but children often do not like their salty taste.

    If your child is only drinking water, you should also encourage them to eat simple foods like fruit or dry crackers. This will give them more energy.

    Care for mild and moderate dehydration

    Babies under six months

    If your child is under six months old and shows any signs of dehydration, take them to see a doctor. They can get sicker very quickly.

    Babies aged six months to one year

    • Feed your child smaller amounts, more often.
    • You could also give your child extra clear fluids for the first 12 hours – especially if they are vomiting or have diarrhoea.
      • You can give them fluids using a syringe (no needle), the same way you do medicine, if they are not feeding as normal. As a general rule, aim to give 5ml (millilitres) every five minutes whenever they are awake.
    • Try these measures for four hours and see how your child responds. If they do not seem to improve or cannot keep anything down, take them to a doctor.

    Children over 10kg (kilograms) – around one year or older

    • Offer your child small sips of fluid often.
      • Aim to give them up to half a cup or 100ml (millilitres) per hour for four hours.
      • They might need more fluid if they are vomiting or have diarrhoea.
    • Switch to clear fluids if your child refuses their normal fluids.
    • It may help to give your child a straw, put their fluids in a sippy cup or use a medicine syringe (no needle).
    • If your child will not drink clear fluids, normal icy poles, jelly, and yoghurt may be good alternatives.
    • Try to avoid fluids high in sugar like lemonade, ginger ale or sports drinks as they can make dehydration worse. However, it is better for them to have some sugary fluids than no fluids at all.
      • Similarly, your child may find it easier to swallow semi-frozen fluids like slushies.
    • Follow this advice for four hours. If your child is still showing signs of dehydration or cannot hold anything down due to vomiting, take them to a doctor or health professional.

    Care for severe dehydration

    If your child has signs of severe dehydration, call an ambulance (000) immediately or take them to your closest hospital emergency department.

    When to get help

    Call an ambulance (000) if:
    • your child has signs of severe dehydration and has trouble breathing.
    • your child has signs of severe dehydration and skin that looks blueish or grey.

    Go to a hospital if:
    • your child has signs of severe dehydration, such as cold hands, sunken eyes, lethargy (low energy), or mottled (reddish-blue patterned) skin.

    See a doctor or health professional if:
    • your child is under six months old.
    • your child has a long-term (chronic) illness, such as heart and kidney problems or gastrointestinal disease.
    • your child takes a medicine that puts them at higher risk of dehydration, such as diuretics.
    • your child’s dehydration is not getting better despite following the advice above, such as giving extra fluids.
    • your child’s symptoms of dehydration do not go away after 24 hours.

    Look after your child at home if:
    • they are drinking enough fluids and urinating (peeing) more than half their normal amount.
    • they do not have any trouble breathing.
    • they get bursts of energy between fevers.
    • they start getting better within seven days.

    Common questions about dehydration

    Should my child drink sports drinks when playing sports to prevent dehydration?

    Exercise can make your child dehydrated if they do not drink enough fluids. However, sports drinks are not recommended for children, as they often have a high sugar content, which can make dehydration worse. Your child should drink extra water during and after playing sports. You could also give them oral rehydration solution.

    What illnesses are most likely to cause dehydration?

    Gastroenteritis is the most common cause of dehydration. This is because people with the illness lose fluids through symptoms like vomiting and diarrhoea, and usually eat and drink less. Conditions that cause a sore throat or sore mouth – such as tonsillitis or hand, foot and mouth disease – can lead to dehydration if the pain makes it harder to eat or drink. High fevers are also linked with dehydration, because the body loses fluids through sweating.

    How can I prevent my child from getting dehydrated?

    When your child is sick, it is important to make sure they drink enough fluids to stop them from getting dehydrated. If your child is well, encourage them to drink water regularly. They should also drink more before, during and after exercise and on hot weather days.

    How much water should my child drink each day when they are well?

    The amount of water your child needs each day when they are well depends on many factors, such as their age, activity levels and lifestyle. For example, if your child plays a lot of sports, they should drink more fluid. As a guide, children aged one to three years should drink about four cups of fluid or 1L (litre) per day; children aged four to eight years old should drink about five cups of fluid or 1.2L per day; children aged nine to 13 years old should drink about five to six cups of fluids or 1.4 to 1.6L per day; and teens aged 14 to 18 should drink about six to eight cups of fluids or 1.6 to 1.9L per day.

    Babies are a bit different, as they get most or all of their daily fluids from breastmilk, formula or food and they do not really need to drink water. In most cases, infants aged zero to six months should get around 0.7L of fluids per day from breastmilk or formula and they do not need to drink water; and infants from seven to 12 months should get around 0.8L of fluids per day from breastmilk, formula and food, and they only need to drink small amounts of water.

    My child cannot keep any fluids down. Should I keep giving them water?

    It is important to keep giving your child fluids when they are vomiting or have diarrhoea. It might seem like the fluids go straight through or get vomited back up, but your child will still absorb a lot of what they drink. The goal is to make sure your child is taking in more fluids than they are losing.

    How is dehydration in children treated in hospital?

    If your child is in hospital for dehydration, they may need medical treatment to help replace lost fluids. This may involve a feeding tube that goes into their stomach via the nose (nasogastric tube), or fluids given directly into a vein through a drip (intravenous or IV therapy).

    Can my child get dehydrated from too much sun?

    Your child can get dehydrated from spending too much time in the sun or on hot days. This is because they lose fluid quickly through sweating to try to cool down, and they may not be able to tell you they need more to drink. It is important to ensure your child has more water when the weather is hot to keep hydrated. They should also wear a hat and long clothing, along with sunscreen SPF50 (Sun Protection Factor 50) or higher on days when the UV (Ultraviolet) rating is three or above – usually from late spring and all through summer.

    For more information

    Developed by The Royal Children’s Hospital Emergency department. We acknowledge the input of RCH consumers and carers.

    Reviewed September 2025

    Please always seek the most recent advice from a registered and practising clinician.


Disclaimer

This information is intended to support, not replace, discussion with your doctor or healthcare professionals. The authors of these consumer health information handouts have made a considerable effort to ensure the information is accurate, up to date and easy to understand. The Royal Children's Hospital Melbourne accepts no responsibility for any inaccuracies, information perceived as misleading, or the success of any treatment regimen detailed in these handouts. Information contained in the handouts is updated regularly and therefore you should always check you are referring to the most recent version of the handout. The onus is on you, the user, to ensure that you have downloaded the most up-to-date version of a consumer health information handout.

Updated July 2025

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