What should you know about green diarrhoea?

Bile starts green and normally changes colour as it travels through the digestive tract. When stool moves quickly, there may be less time for that change, so loose stool can look green. Green foods and colouring can do the same. Gastroenteritis, Food Poisoning and some medicines can speed bowel movement, while Food Intolerance may cause loose stool after a trigger. Less common possibilities include Coeliac Disease, Crohn's Disease, Giardiasis, Hyperthyroidism or Irritable Bowel Syndrome, depending on the wider pattern.

Colour does not identify the cause by itself. Note when the change began, recent foods, travel, medicines, sick contacts, pain, fever and whether anyone else became unwell.

Take frequent small sips of water or an oral rehydration drink, particularly if stools are frequent or you are also vomiting. Eat light foods as tolerated and avoid alcohol. Wash hands carefully and avoid preparing food for others while an infection is possible. Do not use anti-diarrhoeal medicine for bloody stool or high fever without medical advice. Contact a clinician if symptoms do not settle, keep returning, or make it difficult to drink and eat.

Seek urgent help for blood or black stool, severe or worsening abdominal pain, repeated vomiting, confusion, fainting, very little urine, marked drowsiness or signs of dehydration. Children, older adults, pregnant people and those with significant medical conditions can become dehydrated more quickly and should seek advice earlier. Medical review is also appropriate after recent travel, suspected contaminated food or persistent unexplained diarrhoea.

Tell the clinician how often you pass stool, its appearance, your fluid intake, recent travel or antibiotics, and whether there is fever, pain, weight loss or blood.