Causes of watery diarrhoea

A sudden episode may occur with Gastroenteritis or Food Poisoning, especially when loose stools accompany nausea, vomiting, cramps or fever. Giardiasis is another infection that can cause prolonged watery stools after exposure to contaminated water or food.

Repeated symptoms can be associated with Food Intolerance, Irritable Bowel Syndrome, Coeliac Disease or Crohn's Disease. Hyperthyroidism can also speed bowel activity. The pattern matters: note when it began, stool frequency, recent travel, new medicines, dietary changes and whether blood, fever or weight loss is present.

Take frequent small sips of water or an oral rehydration drink, and replace fluids after each loose stool. Eat light foods if hungry, avoid alcohol, and pause foods that clearly worsen symptoms. Wash hands carefully and avoid preparing food for others while illness may be infectious.

A clinician can assess hydration, medicines, exposures and the duration of symptoms. Do not take anti-diarrhoeal medicine if you have blood in the stool or a high temperature unless a clinician advises it.

Seek urgent medical help for fainting, confusion, severe weakness, very little urine, inability to keep fluids down, severe abdominal pain, black stools or visible blood. Arrange medical advice when diarrhoea persists, keeps returning, follows recent travel or antibiotics, or affects an older adult, infant or person with a long-term illness.

Could an infection, food trigger or medicine explain the timing? How can I judge whether I am becoming dehydrated? Do I need stool testing or blood tests, and which foods or drinks should I avoid while recovering?