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Conditions
Gastroenteritis
An infection of the stomach and intestines causing vomiting, diarrhea, and stomach cramps. Often called 'gastro' or 'stomach flu'.
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From $24.95 · No appointment needed
6 min
avg cert turnaround
13 min
avg doctor review
2
days a week
30%
refund if declined
Symptoms
CommonsymptomsofGastroenteritis
An AHPRA-registered doctor assesses these symptoms online - no in-person visit required.
Nausea and vomiting
Watery diarrhea
Stomach cramps and pain
Low-grade fever
Headache
Muscle aches
Loss of appetite
Fatigue
Our Scope
Howwecanhelp
InstantMed handles many common conditions entirely online. Here's what fits our service.
What we can help with
- Medical certificates for gastro-related absences
- Advice on rehydration and symptom management
- Assessment of severity
- Guidance on food handlers returning to work
What needs in-person care
- IV fluids for severe dehydration
- Treatment for bloody diarrhea (requires in-person assessment)
- Care for vulnerable patients with severe symptoms
Depending on your situation, an AHPRA-registered doctor may be able to issue a medical certificate or arrange a repeat prescription after reviewing your request online.
Clinical Guidance
Whentoseeadoctor
These indicators suggest you should seek professional medical advice promptly.
Signs you need a doctor
- 1Symptoms lasting more than 2-3 days
- 2Signs of dehydration (dark urine, dizziness, dry mouth)
- 3Unable to keep fluids down for 24 hours
- 4Blood in vomit or stool
- 5You need a medical certificate for work
Seek emergency care if
- Severe dehydration (confusion, rapid heartbeat, no urination)
- Blood in vomit or stool
- Severe abdominal pain
- High fever over 39°C
- Symptoms in very young children or elderly
Call 000 or go to your nearest emergency department
Clinical Insight
Adoctor'sperspectiveonGastroenteritis
InstantMed Clinical Team
AHPRA-registered medical team · Reviewed 2026-03
Gastro is one of the most common reasons people need a medical certificate, and for good reason - it is genuinely debilitating and highly contagious. The 48-hour rule after your last episode of vomiting or diarrhoea exists because you remain infectious even after feeling better. This is particularly important for anyone working in food preparation, healthcare, childcare, or aged care, where workplace exclusion policies are strict. What we assess is whether your symptoms are consistent with simple viral gastro (the vast majority of cases) or whether there are red flags - blood in the stool, severe dehydration, prolonged high fever, or recent travel - that would warrant in-person assessment. Most gastro resolves in 1-3 days with fluid replacement alone. The biggest risk in otherwise healthy adults is dehydration, which is why oral rehydration solutions are more effective than plain water.
Treatment
TreatingGastroenteritis
Viral gastroenteritis is self-limiting and does not require antibiotics. Treatment is supportive: oral rehydration is the priority. Oral rehydration solutions (ORS) are significantly more effective than plain water or sports drinks because they replace both fluid and electrolytes (sodium, potassium, glucose). Antiemetics (ondansetron) can reduce vomiting in cases where oral rehydration is difficult. Antibiotics are not indicated for viral gastro and are only considered for specific bacterial causes (Campylobacter, Salmonella) in severe or immunocompromised cases.
Oral rehydration salts (ORS)
Hydralyte, Gastrolyte, Pedialyte
Class:Oral electrolyte replacement
Typical dose:Small frequent sips continuously -- 200-400ml per hour in adults; aim for 500ml for each episode of vomiting or diarrhoea
PBS:Available OTC without prescription at any pharmacy or supermarket
- WHO-formula ORS replaces the sodium, potassium, and glucose lost with fluid -- plain water alone is insufficient
- Icy poles (frozen ORS) are useful when nausea makes drinking difficult
- IV fluids are only needed if oral intake is impossible or dehydration is severe
- Continue ORS until normal diet is tolerated and symptoms have resolved
Ondansetron
Zofran, Onsia, Ondansetron Sandoz
Class:5-HT3 antagonist antiemetic
Typical dose:4mg orally every 8 hours for adults; 4mg wafer dissolved under the tongue if swallowing is difficult
PBS:PBS listed for chemotherapy-induced nausea; used off-label for gastroenteritis (general authority or private script); $25.00 general / $7.70 concession (PBS, 2026)
- Effective antiemetic that reduces vomiting and improves ability to maintain oral hydration
- Evidence from randomised trials supports use in adults and children with viral gastroenteritis when vomiting prevents ORS intake
- A telehealth consult can prescribe ondansetron when vomiting is severe
- Avoid in patients with QT prolongation or on other QT-prolonging medications
Source: Therapeutic Guidelines -- Gastrointestinal, 2023; Australian Government Department of Health gastroenteritis management guidelines; NHMRC Australian Drinking Water Guidelines. This information is educational only and does not replace clinical assessment.
Specialist referral: Refer to an emergency department or gastroenterologist if: unable to keep any fluids down for more than 8-12 hours, signs of significant dehydration (very dark urine, dizziness on standing, confusion), bloody diarrhoea, high fever (over 39.5 degrees C), or symptoms in an immunocompromised patient. Bacterial gastroenteritis (Salmonella, Campylobacter) with severe symptoms may require in-person assessment and antibiotic consideration.
Gastroenteritis in Australia
Gastroenteritis causes approximately 1.3 million GP visits in Australia per year
Norovirus is the most common cause of gastro outbreaks in Australia, peaking in winter
Food Standards Australia requires workers who handle food to stay away for 48 hours after symptoms resolve
Children under 5 are most commonly affected, but adults catch gastro 1-2 times per year on average
Recovery
Whattoexpect
Typical recovery timeline and return-to-work guidance for most patients.
Typical recovery
Most viral gastro resolves within 1-3 days. Bacterial gastro (from contaminated food) can last up to a week. Fatigue and reduced appetite may linger for a few days after other symptoms clear.
Return to work
Stay home until 48 hours after your last episode of vomiting or diarrhoea - this is a workplace health requirement, not just a guideline. Food handlers, healthcare workers, and childcare staff must be particularly strict about this. Your employer cannot require you to return earlier.
When to reassess
See a doctor if you cannot keep fluids down for more than 24 hours, notice blood in your vomit or stool, have a fever above 39°C lasting more than 2 days, or feel dizzy or confused - these are signs of dehydration or a more serious infection.
Self-Care
ManagingGastroenteritisathome
Evidence-based tips to support your recovery alongside medical treatment.
Use oral rehydration solutions (Hydralyte, Gastrolyte) rather than plain water - they replace lost electrolytes
Sip small amounts frequently rather than drinking large volumes at once
Avoid dairy, fatty, and sugary foods until symptoms resolve - start with plain crackers, rice, or toast
Wash hands thoroughly with soap and water (hand sanitiser is less effective against norovirus)
Clean contaminated surfaces with bleach-based cleaners, not just regular disinfectant
Avoid preparing food for others until 48 hours after symptoms stop
FAQ
CommonquestionsaboutGastroenteritis
Answers to the most common questions from patients.
You should stay home until 48 hours after your last episode of vomiting or diarrhea. This is especially important if you work with food, healthcare, or childcare.
Yes. Gastroenteritis is a legitimate reason for a medical certificate. Our doctors can provide one after assessing your symptoms.
Focus on clear fluids like water, oral rehydration solutions, and clear broths. Avoid dairy, caffeine, and fatty foods until symptoms resolve. Gradually reintroduce bland foods.
Yes, very. It spreads through contaminated food, water, and contact with infected people. Good hand hygiene is essential to prevent spreading it to others.
Ready to get help with Gastroenteritis?
Australian-registered doctors review your request when available.
Full refund if the doctor declines.