Gastro (Gastroenteritis)
A stomach bug causing vomiting and diarrhoea, usually from a virus such as norovirus or rotavirus. Vomiting usually stops within 1–2 days and diarrhoea within about a week. The job is to keep fluids up and not share it around.
The gastro ladder
Fluids are the treatment. Medicines are occasional helpers. Hospital is for dehydration that sips can’t fix.
- Step 1 · Self-careSmall, frequent sipsA few mouthfuls every 5–15 minutes, even if you’re vomiting. Keep breastfeeding, and eat plain food when you feel ready.
- Works
- Replacing fluids is the main treatment, and most people recover without seeing a doctor
- Cost
- Free
- How long
- Until you’re keeping fluids down and weeing normally
- Watch for
- Avoid lemonade, soft drinks, sports drinks and full-strength juice: too much sugar can make diarrhoea worse.
Sip, don’t chug. Chugging comes straight back up.
- Step 2 · PharmacyOral rehydration solutionSachets, tablets or icy poles that replace water, salt and sugar in the right balance. Good for children, older people and anyone getting dry.
- Works
- Replaces what’s lost in the right balance; the best way to treat or prevent mild to moderate dehydration at home
- Cost
- About $8–15
- How long
- For the worst 1–2 days, or as needed
- Watch for
- Mix exactly as directed. Too strong or too weak doesn’t work as well.
Tastes like sad seawater. Works like a charm.
- Step 3 · PharmacyLoperamide (adults only)An anti-diarrhoea tablet for when you really need a few hours’ break, such as for travel.
- Works
- Slows diarrhoea for a few hours; doesn’t cure the infection
- Cost
- About $5–15
- How long
- Short-term only
- Watch for
- Not for children. Don’t use with blood in your poo unless a doctor says so.
A cork, not a cure.
- Step 4 · PrescriptionAnti-vomiting medicine (ondansetron)Sometimes given to children (and adults) who can’t keep fluids down.
- Works
- In children, about 60% fewer needed a drip or a hospital stay
- Cost
- Under the $25 PBS co-payment when prescribed
- How long
- Usually one dose, sometimes a few
- Watch for
- Can make diarrhoea a little worse. Only when prescribed.
Stops the vomiting long enough for the sipping to work.
- Step 5 · HospitalFluids by drip or nasal tubeFor dehydration that sips can’t fix, or a baby or child who is very unwell.
- Works
- Not a trial question: reliably corrects moderate to severe dehydration
- Cost
- Free in public hospitals
- How long
- Usually hours to a day or two
- Watch for
- Go straight to emergency for the warning signs below.
The backup plan when the sips lose.
Save your money
Popular, heavily marketed or often asked about, but the evidence is weak or says no.
- ProbioticsA 2020 Cochrane review of 82 studies found they made no difference to how many people still had diarrhoea after 2 days.
- Flat lemonade, cola or sports drinksToo sugary, and can make diarrhoea and dehydration worse. Use oral rehydration solution, or water with diluted juice in a pinch.
- Antibiotics “just in case”Most gastro is viral. Even for bacterial gastro, doctors rarely need antibiotics.
What you can do
- Sip fluids every 5–15 minutes. Offer a drink every time a child vomits.
- Keep breastfeeding, and give formula at normal strength.
- Eat plain food when you’re ready. No need to starve the bug.
- Wash hands with soap and water after the toilet or nappies and before handling food.
- Stay home from work, school or childcare until 48 hours after the last vomit or diarrhoea, and don’t prepare food for others.
- Babies: the rotavirus vaccine (given at 2 and 4 months in Australia) protects about 7 in 10 from rotavirus gastro.
See your GP if
- Babies under 6 months with vomiting or diarrhoea
- Children under 3 with a fever over 38°C
- Vomiting for more than 2 days, or diarrhoea for more than a week
- Blood or mucus in your poo
- Signs of dehydration: weeing less, dark urine, dry mouth, dizziness on standing
- You got sick after travel overseas, or you’re older or have a weakened immune system
Call 000 or your local emergency number, or go to emergency, for green vomit, blood in vomit or vomit like coffee grounds, severe or constant tummy pain, a child who is floppy, very drowsy or hard to wake, fewer than 4 wet nappies a day, cold hands and feet with sunken eyes, being unable to keep any fluids down, or a stiff neck with dislike of bright lights.
Common questions
What are the symptoms of gastro?
Diarrhoea, vomiting, nausea, tummy cramps, and sometimes fever, headache and aches. Vomiting often comes first and settles within a day or two.
How does gastro spread?
Through tiny amounts of vomit or poo on hands, surfaces, food or water, and close contact with someone who has it. Norovirus spreads very easily in homes, childcare, cruise ships and aged care.
How is gastro diagnosed?
Usually from the symptoms alone. A poo test is only needed sometimes, for example with blood in the poo, a long illness, recent overseas travel, or an outbreak.
When can I go back to work or school?
48 hours after the last episode of vomiting or diarrhoea. This matters most for food handlers, health and aged-care workers and childcare.
Is it food poisoning or gastro?
Food poisoning is gastro caught from food. The care is the same: fluids, rest and watching for warning signs.
Helpful resources
- Healthdirect: GastroenteritisCauses, rehydration tips, warning signs for adults and children, and a 24/7 nurse line on 1800 022 222. Free, Australia.
- Royal Children’s Hospital Melbourne: GastroPractical guide to giving fluids to babies and children, with clear advice on when to get help. Free, Australia.
- Gastro fact sheet in other languagesThe Royal Children’s Hospital gastro fact sheet translated into many languages. Free.
Evidence and more information
- NHS: Diarrhoea and vomiting
- Healthdirect: Gastroenteritis
- Royal Children’s Hospital Melbourne: Gastroenteritis
- Cochrane (Collinson et al, 2020): Probiotics for acute infectious diarrhoea
- AAFP (2020): Ondansetron for gastroenteritis in children, systematic review data
maladywise.com/gastro/