Gastroenteritis

Understanding Gastroenteritis

Gastroenteritis, commonly known as ‘gastro’, is an infection affecting the digestive tract that leads to inflammation of the stomach and intestinal lining. This widespread condition typically presents with diarrhoea as the primary symptom, often accompanied by vomiting, abdominal discomfort and fever. The infection spreads readily between people, making it highly contagious.

While gastroenteritis usually causes a relatively mild illness in healthy adults, it demands particular attention in certain groups. Older adults, young children and those with compromised immune systems face increased risk of developing more severe symptoms and complications.

What causes Gastroenteritis?

The vast majority of gastroenteritis cases stem from viral infections, with rotavirus and norovirus being the most frequent culprits. Rotavirus particularly affects infants and young children, whilst norovirus more commonly impacts older children and adults. Bacterial infections, including salmonella and campylobacter, account for some cases, as do certain parasites such as giardia and cryptosporidium.

Less commonly, antibiotic use can trigger gastroenteritis by disrupting the natural bacterial balance in the gut. This sometimes leads to an overgrowth of Clostridium difficile, which produces toxins causing inflammation and symptoms.

How Gastroenteritis spreads

This infection transmits primarily through direct contact with an infected person or their bodily fluids. The virus or bacteria present in faeces or vomit can spread when someone touches contaminated surfaces and then touches their mouth. Transmission also occurs through close personal contact, such as shaking hands with someone who hasn’t properly washed their hands after using the toilet.

Contaminated food and water represent another transmission route, sometimes referred to as food poisoning. This occurs when food handlers don’t maintain proper hygiene, or when food and water become contaminated with faecal matter.

Recognising the symptoms

Symptoms typically begin one to three days following exposure to the infection. The illness often starts with nausea and vomiting, which usually persist for one to three days. Diarrhoea follows and may continue for up to ten days, though typically lasts between one and three days.

Additional symptoms may include abdominal cramping and pain, fever, headaches, general weakness and fatigue, and diminished appetite. Some people experience muscle aches and a general feeling of being unwell.

The most significant concern with gastroenteritis is dehydration, which develops when the body loses more fluid through vomiting and diarrhoea than it takes in. Warning signs of dehydration include passing minimal or dark-coloured urine, feeling dizzy upon standing, experiencing excessive thirst, and having dry lips and mouth.

When to seek medical attention

Most adults recover from gastroenteritis without requiring medical intervention. However, you should consult your doctor if you experience severe abdominal pain that worsens, blood or mucus in your stools, a high fever, signs of dehydration (such as passing little to no urine, dark or strong-smelling urine, or feeling faint when standing), or symptoms that persist beyond several days.

Special considerations for children

Babies and young children require particular vigilance as they become dehydrated more rapidly than adults. Seek medical assessment for a child under six months of age, any child weighing less than eight kilograms, those born prematurely or with chronic health conditions, children passing blood in their stools, those experiencing bile-stained (dark green) vomit, children with severe abdominal pain, fever above 38.5°C in children under three years, or signs of dehydration (including fewer than four wet nappies daily, sunken eyes or fontanelle, dry mouth and tongue, cold hands and feet, or unusual drowsiness).

Diagnosis

Your doctor can typically diagnose gastroenteritis by discussing your symptoms and examining you. In most cases, no further testing is required. If symptoms persist or worsen, your doctor may request a stool sample to identify the specific causative organism. This information becomes particularly relevant if bacterial infection is suspected, as some bacterial causes may benefit from antibiotic treatment.

Managing Gastroenteritis at home

The cornerstone of gastroenteritis management involves preventing dehydration by maintaining adequate fluid intake. For adults, sipping clear fluids every five to ten minutes proves more effective than drinking large volumes at once, as this approach is better tolerated when nausea and vomiting are present.

Oral rehydration solutions available from pharmacies (such as Gastrolyte, Hydralyte or Repalyte) contain the optimal balance of glucose and electrolytes to replace what’s lost through vomiting and diarrhoea. If you cannot tolerate these solutions, clear fluids such as water, diluted fruit juice or weak tea remain preferable to dehydration.

Fluid requirements for children

Breastfed infants should continue breastfeeding, potentially with increased frequency. Additional oral rehydration solution or cooled boiled water (for babies under six months) may be offered between feeds. Bottle-fed babies should receive both their usual formula at normal strength and oral rehydration solution.

For children refusing oral rehydration solutions, try chilling the fluid or making ice blocks. If refusal continues, water or diluted juice becomes acceptable, though these don’t contain the ideal electrolyte balance. Avoid undiluted juice, soft drinks, sports drinks and cordials, as their high sugar content may worsen diarrhoea.

Food and nutrition

Modern medical guidance no longer recommends restricting food intake during gastroenteritis. Once the worst of the vomiting subsides and appetite returns, eating can resume. Start with bland, easily digestible foods such as crackers, rice, clear soups, bananas or dry toast. Avoid foods high in sugar, fat or dairy initially, as these may aggravate symptoms.

Children should be allowed to eat when hungry, avoiding only high-sugar foods that might worsen diarrhoea. Infant formula should be given at normal strength, not diluted.
A temporary lactose intolerance occasionally develops following gastroenteritis, particularly in young children. If diarrhoea worsens with milk consumption, becoming watery, frothy or explosive, discuss lactose-free alternatives with your doctor for a few weeks whilst your digestive system recovers.

Medication considerations

Viral gastroenteritis doesn’t respond to antibiotics. Most cases require no medication beyond adequate fluid replacement. Many commonly used anti-vomiting and anti-diarrhoea medications aren’t recommended, particularly for children, as they may cause more harm than benefit.

Paracetamol may help manage fever and discomfort. Always consult your doctor or pharmacist before giving any medication to babies or young children, as many adult preparations prove unsafe for this age group.

Preventing the spread of gastroenteritis

Preventing transmission requires diligent hygiene practices. Wash hands thoroughly with soap and running water after using the toilet, changing nappies, and before preparing or eating food. Hand washing proves more effective than alcohol-based hand sanitisers for gastroenteritis prevention.
Individuals with gastroenteritis should avoid preparing food for others and refrain from attending work, school, childcare or aged care facilities whilst experiencing symptoms and for at least 48 hours after symptoms resolve. This exclusion period helps prevent community spread of the infection.

Clean and disinfect bathroom surfaces regularly, particularly toilets and door handles. Wash contaminated clothing and linen separately using hot water and detergent. Don’t share towels, face washers, toothbrushes or eating utensils whilst someone in the household has gastroenteritis.

Rotavirus vaccination

Vaccination against rotavirus is available for infants and proves highly effective in preventing severe rotavirus gastroenteritis. The vaccine is given orally at two months, four months and possibly six months of age, depending on the vaccine brand used. This vaccination has significantly reduced severe gastroenteritis cases and hospitalisations among young children in Australia.

When recovery takes longer

Whilst most people recover within a week, some experience prolonged symptoms. If diarrhoea persists beyond ten days, or if you’re not regaining strength and returning to normal health, further medical assessment becomes necessary. Your doctor may investigate other potential causes or complications.

Older adults and those with chronic health conditions may require longer recovery periods and closer medical monitoring throughout their illness.

This information has been adapted from patient education resources developed by Health Direct Australia and GESA.