Dehydration & fluid loss: children & teens

About dehydration

Dehydration is a lack of water in your body. If your child loses a lot of body fluids or isn’t drinking enough, they might get dehydrated.

Gastroenteritis is the most common cause of dehydration. This is because it can make your child lose a lot of body fluids quickly. Any health condition that causes persistent diarrhoea, vomiting or reduced fluid intake can result in dehydration.

A lot of sweating can also result in dehydration. This can happen when babies experience very hot weather or adolescent children do vigorous physical activity.

Symptoms of dehydration

Children with mild dehydration might not have symptoms.

Children with severe dehydration might:

wee less often
lose weight
look paler than usual
feel weak, tired, lethargic or irritable
have fewer tears
be thirsty
have a coated and dry tongue and mouth
have sunken eyes and darkening around the eyes
have cold hands and feet.

It can be hard to know whether younger children are weeing less often. The best way to tell is by checking their nappies. They might have fewer wet nappies, or their nappies might not be as wet as usual.

Medical help: when to get it for dehydrated children and teenagers

You should see your GP if your child is under 6 months and has vomiting or diarrhoea.

If your child is older than 6 months, you should take them to the GP if they:

wee less often
have been vomiting often, can’t keep any fluids down, or have been vomiting for more than 24 hours
have diarrhoea lasting longer than 2 weeks
aren’t gaining weight or are losing weight because of vomiting or diarrhoea.

Go to a hospital emergency department or call 000 for an ambulance straight away if your child seems very unwell or has symptoms of severe dehydration:

no wee
skin that’s paler than usual
sunken eyes, cold hands and feet
drowsiness or irritability.

You know your child best. If your child seems unwell, seek medical attention. Signs that your child has a serious illness that needs urgent medical attention include severe pain, drowsiness, skin that looks grey or paler than usual, dehydration, troubled breathing, seizures and reduced responsiveness.

Treatment for dehydration

Mild dehydration
You can treat mild cases of dehydration by giving your child more fluid.

One option is oral rehydration fluid like Gastrolyte, Hydralyte, Pedialyte or Repalyte. You can buy these fluids over the counter from a pharmacy or supermarket. These products might come as premade liquid, soluble tablets, powder or icy poles for freezing. Make sure that you make up the liquid carefully according to the instructions on the packet.

If you can’t get oral rehydration fluid, you can use diluted lemonade, cordial or fruit juice. If you’re using a sugary drink, it’s important to dilute it – use 1 part of lemonade, cordial or juice to 4 parts water.

If your child doesn’t want to drink, try to get them drinking more by offering fluids via a syringe, spoon or straw. Or it might help to chill drinks first. Your child could also suck icy poles.

If your child is vomiting, it’s usually better to offer small amounts of fluid, but more frequently. For example, give your child a few mouthfuls every 15 minutes.

If you have a breastfed baby, keep breastfeeding but feed more often. You can also give your baby oral rehydration fluid between increased feeds.

If your baby is bottle fed, give them only oral rehydration fluid for the first 24 hours and then reintroduce full-strength formula in smaller, more frequent feeds. You can still offer extra oral rehydration fluids between feeds.

Severe dehydration
In more severe cases of dehydration, your child will need to go to hospital to catch up on fluid loss.

In many cases, the safest and quickest way for your child to get the fluid they need is via a small tube that goes into their nose and then into their stomach. The rehydrating fluids go through this tube. Less often, your child will be given fluids into a vein.

Prevention of dehydration

The best way to avoid severe dehydration is to see your doctor if your child has a health condition that’s causing them to lose a lot of fluid or stop drinking.

On hot days or when your child is exercising, they need to stay hydrated. Make sure there’s plenty of water handy so your child can drink if they’re thirsty. You might need to remind some children to have regular drink breaks.