Yellow diarrhoea: what to know

Bile is a yellow-green digestive fluid. When bowel contents travel faster than usual, there may be less time for bile pigments to change colour, so loose stool can look yellow. A short-lived episode may follow a stomach infection, a food-related upset, or a change in diet. Greasy, floating stool, weight loss, recurrent episodes, or symptoms after particular foods can point to a digestion problem that deserves review.

Food poisoning and gastroenteritis can cause diarrhoea alongside cramps, nausea, vomiting, or fever. Giardiasis may be considered after exposure to unsafe water or persistent bowel upset. Coeliac disease, Crohn's disease, food intolerance, irritable bowel syndrome, and hyperthyroidism are examples of conditions that can be discussed when symptoms keep returning.

Drink small, frequent amounts of water or an oral rehydration drink, especially after each loose stool. Eat when you feel able, choosing simple foods that you tolerate, and avoid alcohol or very fatty foods while the bowel is unsettled. Wash hands carefully after using the toilet and before preparing food to reduce spread if an infection is involved.

Make a brief note of when the diarrhoea started, recent travel, meals, medicines, fever, pain, and whether stool is oily or contains blood. This gives a clinician useful detail if the problem does not settle.

Seek urgent medical care for blood or black stool, severe or worsening abdominal pain, confusion, fainting, very little urine, or an inability to keep fluids down. Arrange a prompt appointment if diarrhoea persists, keeps coming back, follows travel, or comes with unplanned weight loss, fever, or yellowing of the skin or eyes. Babies, older adults, pregnant people, and people with weakened immunity can become unwell more quickly from fluid loss.

Ask whether your pattern suggests infection, poor absorption, medicine effects, or another bowel condition, and whether stool or blood tests would help. Mention any recent antibiotics, overseas travel, new supplements, and family history of bowel disease. Ask how to maintain fluids safely and which symptoms should change your plan.