Noticing that your stool has turned yellow can be alarming. Many people jump online to search “why is my poop yellow” or “yellow colored diarrhoea” because it feels unusual and worrying. While changes in bowel movements are often linked to what you eat, sometimes they can signal an underlying digestive issue.
In this article, we’ll explore the common reasons for yellow poop, yellow loose bowel movements, and even bright yellow diarrhoea. We’ll also take a quick look at the “rainbow of poop” what different stool colours can mean, plus when it’s time to seek medical advice.
What does normal stool look like?
Most of the time, stool is brown because of bile, a fluid made by your liver to help digest fats, and bilirubin, a substance formed when red blood cells break down. As bile travels through your gut, it changes colour from yellow-green to the typical brown we expect.
If stool appears yellow instead of brown, it often means bile hasn’t been processed in the usual way, or that food is moving through your system too quickly.
Common causes of yellow poop and diarrhoea
-
Diet and food colourings
Certain foods can temporarily make your stool yellow. Eating lots of carrots, sweet potatoes, turmeric, or foods with yellow dyes may change stool colour without being a health concern. Greasy or fatty meals can also lead to yellow loose bowel movements.
-
Gut infections and parasites
Infections like viral gastroenteritis or parasites (e.g. Giardia) can cause bright yellow diarrhoea. These bugs speed up digestion and reduce absorption, so bile doesn’t fully break down. This usually comes with cramps, nausea, or fever.
-
Food intolerances and malabsorption
If your body struggles to digest fats, stool may look yellow, greasy, or loose. This can happen with lactose intolerance, coeliac disease, or conditions that affect the small intestine.
-
Gallbladder or bile problems
The gallbladder stores bile, which helps break down fat. If bile flow is blocked (e.g. by gallstones) or reduced, stool may appear pale, clay-coloured, or yellow. Pain in the upper right side of the abdomen often accompanies these issues.
-
Pancreatic conditions
The pancreas produces digestive enzymes. If it’s inflamed (pancreatitis) or under-functioning, fat digestion suffers, leading to yellow, oily stools that may float.
-
Liver-related conditions
Because the liver produces bile, issues like hepatitis or cholestasis can also change stool colour. Yellow stool with dark urine or yellowing of the skin/eyes (jaundice) requires urgent medical attention.
The rainbow of poop: what different colours can mean
Your stool can sometimes act like a health “check engine” light. While brown is the usual colour, other shades can appear, and most have fairly simple explanations.
-
Brown (normal): The standard colour thanks to bile and bilirubin breakdown.
-
Green: Common after eating green veg, food colourings, or when food moves quickly through the gut (so bile doesn’t fully break down).
-
Yellow: May indicate fat malabsorption, rapid digestion, or diet-related causes.
-
Black or very dark: Could be linked to iron supplements, certain foods (like black liquorice or blueberries), or upper GI bleeding, which needs urgent medical review.
-
Red: Sometimes from foods like beetroot or tomato, but can also indicate bleeding in the lower digestive tract. Always worth checking with a doctor if unexplained.
-
Pale, clay-coloured, or white: May signal a lack of bile flow, possibly due to gallbladder or liver issues.
Occasional changes are often linked to diet. But if you consistently notice unusual colours (especially black, red, or pale stools), it’s best to get medical advice.
Bright yellow diarrhoea vs. yellow poo: what’s the difference?
- Bright yellow diarrhoea often means food is moving too quickly through the gut, such as during infections, stress, or after certain meals.
- Yellow poo (formed, not watery) may be more linked to fat digestion, bile flow, or diet.
Both can overlap, but if it’s persistent or severe, it’s best to speak with a healthcare provider.
When to see a doctor
Yellow stool isn’t always serious, but watch for these red flags:
- Persistent yellow diarrhoea lasting more than a few days
- Unexplained weight loss
- Severe abdominal pain or cramps
- Blood in stool or black, tarry stool
- Yellowing of skin or eyes (jaundice)
- Signs of dehydration
These can point to underlying conditions that need medical care.
Everyday gut support
For most people, occasional yellow poop or yellow loose bowel movements are linked to diet or short-lived infections. To support everyday gut health:
- Eat a varied, fibre-rich diet
- Stay hydrated
- Limit high-fat and heavily processed foods
- Pay attention to any food triggers
The bottom line
If you’re wondering “why is my poop yellow”, know that the cause is often dietary or temporary. But if you have ongoing yellow colored diarrhoea, bright yellow diarrhoea, or symptoms like pain, weight loss, or jaundice, it’s important to check in with your doctor.
Your gut health is central to your overall well-being. By listening to your body, supporting digestion with nourishing foods, and seeking medical guidance when needed, you can stay on top of what your bowel movements are telling you.
Reviewed by
