What is dehydration?

Dehydration occurs when you don't have enough fluid in your body. If you are dehydrated, your body can't function properly.

Your body needs fluids to:

• keep your body temperature stable
• move nutrients around your body
• move waste out of your body

When your body has enough water to work properly, you are hydrated.

What symptoms are related to dehydration?

If you have mild to moderate dehydration, you might:

• be thirsty
• have a dry mouth, lips and tongue
• be dizzy or light-headed, particularly when standing up
• have a headache
• have dark urine (wee)
• wee a less than usual
• have a fever

Signs of mild dehydration in babies and toddlers include fewer wet nappies or nappies that are not as wet as usual. Older children may not go to the toilet as often.

If you have severe dehydration, you might:

• be extremely thirsty
• be breathing fast, have a fast heart rate and have low blood pressure
• be irritable, tired, or confused
• have cold hands and feet
• be pale
• have sunken eyes

Babies who are severely dehydrated may have a sunken fontanelle. The fontanelle is the soft spot on top of your baby's head.

What causes dehydration?

Dehydration can happen when your body loses too much fluid.

You might become dehydrated if you:

• don't drink enough water
• have severe vomiting or diarrhoea
• have a fever
• drink too much alcohol
• do strenuous exercise, especially in hot weather
• take certain medicines, such as diuretics
• have diabetes

Some people have a higher chance of becoming dehydrated. This includes:

• babies
• young children
• older adults

Dehydration in babies and young children

Babies and young children have a higher chance of becoming dehydrated than adults.

A baby or young child can quickly become dehydrated if they:

• are vomiting
• have a fever
• have diarrhoea
• are unwell for any reason
• are not feeding or drinking enough

Dehydration in older people

Older people can become more easily dehydrated because of:

• poor kidney function
• limited mobility
• use of medicines such as diuretics

Dehydration in older people can cause problems such as:

• confusion
• constipation
• falls
• stroke

Older people may not notice that they are feeling thirsty. If you're caring for an older person, remind them to drink regularly.

How is dehydration diagnosed?

Your doctor will ask you about your symptoms and examine you. They may recommend tests, such as a urine test or blood tests.

This way, they can investigate what is causing your dehydration.

When should I see my doctor?

If you are concerned that you are dehydrated, see your doctor.

See your doctor as soon as possible if your baby is under 6 months old and has signs of mild dehydration. Young babies can go from mild to severe dehydration very quickly.

When to seek urgent care

People of any age with severe dehydration need urgent medical care.

How is dehydration treated?

Severe dehydration needs immediate medical treatment. In hospital, you will get fluids through an intravenous (IV) drip.

Self-care at home

If you experience any mild symptoms of dehydration, you should:

• move to a cool place
• loosen any tight clothing and remove unnecessary clothes
• drink small amounts of cool water regularly

Some fluids can make dehydration worse. You should avoid:

• sugary drinks like soda and sports drinks
• caffeine
• alcohol

Medicines for dehydration

Oral rehydration solutions can help if you are dehydrated. You can find these in your pharmacy and supermarket. You can speak to your doctor or pharmacist about which solutions are best for you or your child.

You can also make a rehydration solution at home. In 1 litre of water, add:

• 6 teaspoons of sugar
• 1/2 a teaspoon of salt
• 1/2 a teaspoon of sodium bicarbonate

You should speak to your doctor before giving homemade rehydration solution to your child. You should also check with your doctor first if you:

• have diabetes
• are pregnant
• are breastfeeding

What are the complications of dehydration?

Being severely dehydrated can cause serious problems. It can impact your organs, such as your kidneys and your heart.

Severe dehydration can be life threatening.

Can dehydration be prevented?

To prevent dehydration, make sure you drink enough water each day.

As a general guide, children over 1 year old should drink around 1 to 2 litres a day.

Adults should drink around 2.1 to 2.6 litres of fluid a day.

Have extra fluids:

• when you're exercising
• in hot weather
• when you're sick

Water is the best drink to hydrate your body.

Children under 6 months of age should not drink water or dairy milk. You can read about more hydration tips for children.

Resources and support

To learn more, read Kidney Health Australia's Drink Water Instead factsheet.

You can find information on dehydration in languages other than English through the Health Translations website.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.