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Gastroenteritis, or “gastro”, is an infection of the gut that causes diarrhoea, vomiting or both. It’s very common in Australia, spreads easily between people, and usually settles by itself within a few days. The main risk is dehydration, especially for babies, young children, older people and anyone with other health conditions.
This article explains what causes gastro, the symptoms to look out for, how it spreads and how to protect your household. For practical tips on fluids, food and caring for a sick child, see our companion guide, Managing gastro at home: fluids, food and when to get help.
What is gastroenteritis?
Gastroenteritis is inflammation of the stomach and bowel, usually caused by an infection. People often call it “stomach flu”, but it has nothing to do with influenza, which is a respiratory virus.
Most cases are caused by viruses and get better without specific treatment. Gastro can happen at any time of year, but outbreaks are common wherever people are in close contact, such as childcare centres, schools, aged care homes, hospitals and cruise ships.
Common symptoms
Symptoms often start suddenly, usually within a day or two of catching the infection. They can include:
- diarrhoea (loose or watery poo)
- nausea and vomiting
- stomach cramps or pain
- fever
- loss of appetite
- headache, tiredness and aching muscles
According to healthdirect, vomiting usually lasts a day or two, and diarrhoea usually lasts a few days but can continue for up to 10 days.
Signs of dehydration
Diarrhoea and vomiting can drain the body of fluid quickly. Watch for:
- feeling very thirsty, with a dry mouth or lips
- passing less urine, or dark urine
- dizziness or light-headedness, especially when standing
- unusual tiredness or drowsiness
- in babies and young children: fewer wet nappies, no tears when crying, sunken eyes, or being floppy or unusually sleepy
Dehydration needs prompt medical attention, particularly in babies and young children. See “When to get urgent help” below.
What causes gastro?
Gastro can be caused by viruses, bacteria or parasites.
| Type | Common examples | How people usually catch it |
|---|---|---|
| Viruses (most common) | Norovirus, rotavirus, adenovirus | Contact with an infected person, contaminated surfaces, or food prepared by someone who is unwell |
| Bacteria | Campylobacter, Salmonella, some types of E. coli | Undercooked meat, poultry or eggs, unwashed produce, or food left out of the fridge (often called food poisoning) |
| Parasites | Giardia, Cryptosporidium | Untreated water from creeks, tanks or overseas water supplies, or swimming pools |
Less often, diarrhoea and vomiting can be caused by things other than infection, such as a reaction to a medicine or another bowel condition. If symptoms keep coming back or don’t settle, it’s worth seeing a doctor.
How gastro spreads
Gastro germs are found in the vomit and poo of an infected person. Tiny amounts can spread through:
- unwashed hands, especially after using the toilet or changing nappies
- touching contaminated surfaces such as taps, door handles, toys and toilet seats
- eating food or drinking water that has been contaminated
- particles in the air when someone vomits, which is common with norovirus
People can be infectious while they have symptoms and for a while after they feel better. That’s why the advice is to stay home until symptoms have well and truly stopped.
How to prevent gastro and stop it spreading
Wash your hands well
Wash with soap and running water for at least 20 seconds, then dry thoroughly. Do this after using the toilet, changing nappies or cleaning up vomit, and before preparing or eating food. Alcohol hand rubs are handy, but they don’t work as well against some gastro viruses such as norovirus, so soap and water is best.
Stay home while you’re infectious
Healthdirect advises that children and adults shouldn’t return to school, childcare or work until 48 hours after the last episode of diarrhoea or vomiting. If you work with food, in health care, in aged care or in childcare, check your workplace’s rules, as they may be stricter.
Clean up carefully
- Wear disposable gloves when cleaning up vomit or diarrhoea.
- Clean the area with detergent and hot water, then disinfect with a bleach-based product, following the label instructions.
- Wash soiled clothing and linen on a hot wash cycle.
- Don’t share towels, face washers or cutlery with someone who is unwell.
Handle food safely
- Don’t prepare food for others while you have symptoms and for 48 hours afterwards.
- Cook meat, chicken and eggs thoroughly.
- Keep raw and cooked foods separate, and use different chopping boards.
- Refrigerate leftovers promptly.
- Wash fruit and vegetables before eating them.
Vaccination for babies
Rotavirus used to be a common cause of severe gastro in young children. A rotavirus vaccine is now part of the routine childhood immunisation schedule, given as drops by mouth at 2 and 4 months of age. There is currently no vaccine for norovirus.
When travelling
Where the water may not be safe, drink bottled or treated water, avoid ice, and be careful with raw foods.
When to see a GP
Most people with gastro can be cared for at home. See a doctor if:
- you can’t keep fluids down, or you’re worried about dehydration
- symptoms haven’t started to improve after a few days
- you have a fever, blood in your poo or severe stomach pain
- you’re pregnant, older, or have a long-term condition such as diabetes, kidney disease or a weakened immune system
- you’ve recently travelled overseas
- a baby or young child has gastro (healthdirect advises that babies under 6 months with suspected gastro should always be seen by a doctor)
A doctor may ask for a stool (poo) sample to check for bacteria or parasites, particularly if symptoms are severe, bloody, long-lasting or travel-related. Antibiotics don’t help viral gastro and are only needed in some specific situations, which your doctor will discuss with you.
When to get urgent help
Call 000 or go to your nearest emergency department if you or someone you’re caring for:
- is very drowsy, confused or hard to wake
- has signs of severe dehydration, such as not passing urine, very few wet nappies, cold hands and feet, or fast breathing
- can’t keep any fluids down
- has severe or constant stomach pain
- has a lot of blood in their poo or vomit, or green vomit
- is a baby under 3 months with a fever of 38°C or higher
How Teldoc can help
Our AHPRA-registered GPs can talk through gastro symptoms by phone or video, 7 days a week from 9 am to 7 pm (Sydney time). Most patients are seen within 15 minutes. Your doctor can:
- check for signs of dehydration or something more serious
- give advice on fluids and managing symptoms
- prescribe treatment if clinically appropriate, with an eScript sent to your phone
- arrange a stool test through our pathology referrals if needed
- provide a medical certificate for work or study, or a carer’s leave certificate if you’re looking after a sick child
- let you know if you need to be seen in person
General consultations are $55 on weekdays and $75 on weekends and public holidays. Babies under 12 months are bulk billed with a valid Medicare card. See our fees page for details, or read more about our online gastro consultations.
Frequently asked questions
How long is gastro contagious?
You can spread gastro while you have symptoms and for a while afterwards. Stay home from work, school or childcare until 48 hours after your last episode of vomiting or diarrhoea, and keep washing your hands well.
Is gastro the same as food poisoning?
Food poisoning is one cause of gastro. It happens when you eat food contaminated with bacteria, viruses or toxins. Many cases of gastro aren’t food-related and are passed from person to person instead.
Do I need antibiotics for gastro?
Usually not. Most gastro is caused by viruses, which antibiotics don’t treat. A doctor may consider them for some bacterial or parasitic infections, often after a stool test.
Does hand sanitiser kill gastro germs?
Alcohol hand rubs don’t work as well against some gastro viruses, such as norovirus. Washing with soap and running water for at least 20 seconds is the best option.
Is there a vaccine for gastro?
There’s a rotavirus vaccine for babies, given at 2 and 4 months as part of the routine childhood immunisation schedule. There’s no vaccine for norovirus or most other causes of gastro.
This article is general health information and isn’t a substitute for advice from your own doctor. If you’re worried about your health, speak to a GP. In an emergency, call 000.
Medically reviewed by Dr Vafa Derakshan (MBBS, FRACGP), September 2026
