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 illness that causes persistent diarrhoea, vomiting or reduced fluid intake can result in dehydration.

A lot of sweating can also result in dehydration, particularly in babies in very hot weather, or in adolescent children who are doing vigorous activity.

Symptoms of dehydration

Children with mild dehydration might not have symptoms.

Children with severe dehydration might:

urinate less often
lose weight
look pale
be tired, lethargic or irritable
have fewer tears
be thirsty
have sunken and dark eyes
have a coated and dry tongue and mouth.

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.

Does your child need to see a doctor about dehydration?

In some cases, yes.

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:

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.

Take your child to a hospital emergency department straight away if they:

have symptoms of severe dehydration – they are not urinating, are pale and thin, have sunken eyes, cold hands and feet, and are drowsy or cranky
seem very unwell.

You know your child best, so trust your instincts if your child doesn’t seem well. Signs that your child has a serious illness that needs urgent medical attention include severe pain, drowsiness, pale or blue skin, 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 tablet, 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 one part of lemonade, cordial or juice to four parts of water.

Your child might not want to drink extra fluids. You can encourage them to drink more by giving them drinks with a syringe or spoon, or letting them 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 give your child extra oral rehydration fluid between feeds.

If your baby is bottle fed, give them oral rehydration fluid for the first 24 hours only 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 might need to go to hospital to catch up on fluid loss. In many cases, the safest and quickest way to do this is by via a small tube that goes into your child’s nose and then into their stomach. The rehydrating fluids go through this tube. Less often, your child will be given fluids indirectly into a vein.

Prevention of dehydration

The best way to avoid severe dehydration is to see your doctor if your child has an illness 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.