03 August 2026
Diarrhoea means passing three or more loose or liquid stools per day or passing loose stools more often than is normal for you. It can have several causes, including infection and food-related triggers.
Common Causes of Diarrhoea
Diarrhoea occurs when your intestines move stool through your digestive tract too quickly or when excess fluid is secreted into the bowel.
Common causes include:
1. Viral Infections
Viral infections such as norovirus and rotavirus can cause gastroenteritis. Symptoms may include diarrhoea, vomiting, stomach pain or cramps, nausea and fever. Most cases of gastroenteritis improve within a few days and do not require treatment, although symptoms can sometimes last longer.
2. Bacterial Infections and Food Poisoning
Campylobacter, E. coli and Salmonella are bacteria that can be found in infected people or animals, water and some foods. Infection can occur after eating contaminated raw or undercooked food, drinking contaminated water, consuming raw unpasteurised milk products or touching contaminated surfaces and then touching your mouth.
These infections may cause diarrhoea, which may contain blood, stomach pain or cramps, nausea, vomiting, fever and fatigue.
3. Dietary Causes
Foods and drinks affect people differently. Possible triggers include:
- Fried, greasy or high-fat foods.
- Caffeine-containing drinks or foods.
- Alcohol.
- Dairy products in people with lactose intolerance.
- High levels of sugar alcohols such as sorbitol, mannitol or xylitol.
Can Symptoms Tell You Whether it is Viral or Bacterial?
It is not always possible to tell whether gastroenteritis is viral or bacterial from symptoms alone. Blood in the stool, severe abdominal pain, high fever or worsening illness should prompt medical advice, but testing may be required to identify the cause.
When to Seek Help
See a healthcare provider if symptoms are severe or worsening, are not going away after three or four days, or include blood in the diarrhoea or vomit, severe stomach pain, repeated vomiting that prevents you keeping fluids down, or signs of dehydration.
This information is provided for general educational purposes only and is not intended to constitute medical advice, diagnosis, or treatment.
Speak with your healthcare professional for advice that reflects your individual health needs