What is gastroenteritis?

Gastroenteritis (also known as ‘gastro’) is a common and very contagious infection of the gut (the stomach and intestines). It causes inflammation of the lining of your digestive system. Gastro usually causes a mild illness that involves vomiting, diarrhoea, stomach pains and nausea.

Older people, young children and those with a weakened immune system are at a higher risk of developing more severe symptoms.

What causes gastroenteritis?

Gastro may be caused by:

• viruses are the most common cause, including rotavirus and norovirus
• bacteria, such as salmonella, campylobacter
• toxins produced by bacteria such as clostridium difficile
• parasites, such as giardia and cryptosporidium

Viruses that cause gastro are very contagious. They are found in human faeces (poo). Viral gastro spreads when you have contact with infected vomit or faeces.

Viral gastro can spread through:

• contaminated food, drinks or objects
• person to person contact — coughing, sneezing or shaking hands with someone who is sick and has virus on their hands

Some bacteria and parasites that cause gastro are found in contaminated food or water — this is sometimes called ‘food poisoning’. Food poisoning symptoms usually begin 6 to 12 hours after eating spoiled food.

Gastro caused by vlostridium difficile (also known as ‘c. diff’) usually results from antibiotic use. Clostridium difficile commonly lives in the gut of many people in small amounts without causing problems. Taking antibiotics can reduce the variety of bacteria that live in your gut — both those that cause symptoms and healthy or ‘good’ bacteria. This results in an imbalance in your gut bacteria that give clostridium difficile the opportunity to multiply more than usual and cause symptoms.

Read more on gut health.

Should I keep my child home from school?

Here’s a list of common childhood illnesses, including gastroenteritis, and their recommended exclusion periods.

What are the symptoms of gastroenteritis?

If you have gastro, you may have some of these symptoms:

• nausea and vomiting
• diarrhoea
• stomach pains and cramping
• fever, body aches, weakness, tiredness
• headaches
• loss of appetite

Vomiting usually lasts 1 to 2 days. Diarrhoea usually lasts around 1 to 3 days, but can last up to 10 days.

If you have severe gastro, you may:

• be unable to keep down any fluids
• pass less urine (wee)
• feel faint when you stand up

When should I see my doctor?

Adults and older children

You should see your doctor if you have:

• severe abdominal (tummy) pain that is getting worse
• frequent vomiting or diarrhoea
• blood or mucus in your poo
• a fever
• signs of dehydration for example, passing little or no urine, urine that is dark or smelly or feeling faint or dizzy when standing
• other symptoms that concern you

Young children

Your young child should see a doctor if they:

• are less than 6 months old
• are less than 3 years old and have a fever over 38.5℃
• weight less than 8kg
• were born prematurely, or have other health problems
• pass blood in their poo, have dark green vomit or have severe stomach pains
• are unable to keep food or fluids down without vomiting
• are not getting better, or you are worried

You should also take your child to a doctor if they have symptoms of significant dehydration, such as:

• excessive sleepiness or drowsiness
• severe thirst
• less than 4 wet nappies a day
• cold hands and feet
• dry lips and tongue
• sunken eyes and/or fontanelle
• fast breathing

How is gastroenteritis diagnosed?

Your doctor can diagnose gastro by examining you and ask about your symptoms. If you’re not getting better, your doctor may recommend a stool (poo) test to check what is causing your illness.

How is gastroenteritis treated?

If your gastro is caused by bacteria or parasites, they may prescribe antibiotics. Viral gastroenteritis does not need antibiotics. Read more on the differences between bacterial and viral infections.

Most people recover from gastro on their own without needing treatment from a doctor.

If you become severely dehydrated, you may need fluids in an intravenous drip.

Tips to manage gastro symptoms:

• Drink plenty of fluids to avoid dehydration. Sip clear fluids every 5 to 10 minutes. These help replace fluids lost by vomiting and diarrhoea. Avoid drinks that are high in sugar, as they can make diarrhoea worse.
• Eat if you feel hungry. Start with bland foods such as crackers, rice, clear soup, a banana or dry toast.
• Rest as much as you can.
• Continue breastfeeding as normal.
• Sek medical advice before taking anti-nausea or anti-diarrhoea medicines. Do not give anti-diarrhoea medicines to children.

Babies and children with gastro

The most common and serious complication of gastro in babies and children is dehydration. Children with health problems may become dehydrated more quickly.

If your baby is under 6 months of age, take them to a doctor if you think they have gastro. If they are older, it is still a good idea for them to be checked in case they are dehydrated.

If you cannot find rehydration fluids, or your child refuses to drink them, try diluted fruit juice (1 part juice to 4 parts of water). You can also try a cube of ice or an iceblock

It’s important to continue to breastfeed your baby. Your baby may need to feed more frequently. You can also give rehydration fluid between feeds, if your baby needs to drink more. If you are feeding your baby with formula, give them the usual amount of formula, and then give them rehydration fluids if they’re still thirsty.

Many medicines that are commonly used by adults or older children to stop vomiting or diarrhoea can be dangerous for babies. Make sure to ask your doctor or pharmacist before giving your baby any medicines.

Older people with gastro

Older people are at a higher risk of having complications from gastro. They are at a higher risk of becoming severely dehydrated, and are more likely to need an intravenous (IV) fluid drip to replace fluids lost from diarrhoea or vomiting.

Gastro outbreaks are common in aged-care facilities. Older people may also experience symptoms that mimic gastro, such as those caused by conditions such as chronic bowel disease or medicines.

Can gastroenteritis be prevented?

Here is how you can reduce the chance of spreading gastro:

• If you have been sick with gastro and work in health care, residential or aged care or the food industry, do not go to work until 48 hours after your last episode of vomiting or diarrhoea.
• Wash and dry your hands after using the bathroom, changing nappies, cleaning up vomit or diarrhoea and before eating or preparing food.
• Wash clothing or bedding contaminated with vomit or diarrhoea using detergent and hot water. Clean bathrooms and toilets often.
• Do not share your towels, face washer, toothbrush, drinkware or cutlery.
• Avoid preparing or handling food for others while you are unwell.
• If you think your illness has been caused by food, report it to your local council’s health department. Keep leftovers for testing.

You can reduce your chance of catching gastro:

• Avoid contact with people with gastro.
• Store and cook foods according to health regulations.
• Take care when handling animals and their faeces (poo) and urine (wee).
• Handle and prepare raw and cooked foods separately and cook well.

If you are travelling to places with poor hygiene or where the local tap water is not safe to drink, here are some tips:

• Only use bottled water for drinking and brushing your teeth.
• Don't put ice in drinks.
• Eat fruit you can peel yourself.
• Avoid uncooked foods, including salads.

Children and vaccination for rotavirus

Rotavirus is a virus that causes severe gastroenteritis in babies and young children. All young children should receive the rotavirus vaccine at 2 months of age (6 to 8 weeks old) and 4 months of age. A third dose at 6 months of age may be needed, depending on the brand of vaccine used.

This vaccine is effective in preventing rotavirus infection in about 7 out of every 10 children vaccinated. Read more on immunisation and vaccinations for your child.

Resources and support

• Download Sydney Children’s Hospital factsheets on gastroenteritis in children — in English, Chinese, Greek and Italian.
• Visit the GESA (Gastroenterological Society of Australia) website, where you can find more information on gastro in kids.
• For tips about staying hydrated, see drinking water and your health.

Do you prefer to read in languages other than English?

• The Victorian Department of Health has developed fact sheets about gastroenteritis in Greek, Arabic, Italian, Serbian and other community languages.