The best way to treat dehydration is to rehydrate the body by drinking plenty of fluids, such as water, semi-skimmed milk, diluted squash or diluted fruit juice.

A sweet drink can help replace lost sugar and a salty snack can help replace lost salt.

Babies

If your baby is dehydrated, take them to see your GP as soon as possible. They'll be able to recommend appropriate treatments such as those outlined below.

Give your baby plenty of liquids, such as breastmilk or formula. It can often be better to give them smaller amounts of fluid more frequently.

Don't dilute your baby's formula (if you use it). Babies who are formula fed and those on solids can be given extra water.

Avoid giving your baby fruit juice, particularly if they have diarrhoea and vomiting because it can make it worse.

Giving your baby regular sips (a few times an hour) of oral rehydration solution (ORS) with their usual feed (breastmilk, formula milk and water) will help replace lost fluids, salts and sugars.

Infants and children

Infants and children who are dehydrated shouldn't be given only water because it can dilute the already low level of minerals in their body and make the problem worse. Instead, they should have diluted squash, diluted fruit juice or a special oral rehydration solution (see below).

If you or your child is finding it difficult to hold down fluids because of vomiting or diarrhoea, take smaller amounts more frequently. You may find it easier to use a spoon or a syringe to give your child small amounts of fluid.

Read more about vomiting in adults and vomiting in children and babies.

Oral rehydration solutions

When you're dehydrated, you lose sugar and salts as well as water. Drinking a rehydration solution will enable you to re-establish the right balance of body fluids. The solution should contain a mixture of potassium and sodium salts, as well as glucose or starch.

There are several different rehydration products available over-the-counter from pharmacies or on prescription from your GP, including solutions that are suitable for infants and children.

Ask your GP or pharmacist for advice about the most suitable rehydration solution for you or your child.

Severe dehydration

Seek immediate medical help if you suspect someone is severely dehydrated (see symptoms of severe dehydration).

They may need to be admitted to hospital for treatment. In particular, babies, infants and elderly people will need urgent treatment if they become dehydrated.

Fluid may be given up the nose using a nasogastric tube or using a saline drip into a vein (intravenously). This will provide essential nutrients faster than using solutions that you drink.

If you have had bowel surgery, some rehydration solutions may not contain enough salt. In this case, you will need a higher-strength solution. Your GP or surgeon will be able to recommend a suitable rehydration solution for you.