Yellow poo: Why it happens and what to do

Although poo is usually brown, it’s perfectly normal for the colour to change, depending on what you've eaten. 

Some common factors that can change the shade are beetroot, green vegetables, food dyes and certain supplements.

Yellow poo or diarrhoea can also stem from certain health conditions. These may be gut infections, coeliac disease, inflammatory bowel diseases (IBDs) and problems with your liver, gallbladder or pancreas.

Below, we’ll explore each of the possible causes and explain when to see a doctor.

But whatever the cause of your diarrhoea, it’s important to stay hydrated by drinking plenty of fluids.

10 causes of yellow poo or diarrhoea

There are many possible causes of yellow poo, which may be watery and frequent. Your diet, certain medications and supplements, and a number of health conditions could be involved.

Before we look at the causes in more detail, it’s worth understanding these medical terms:

• Bile: This yellow-green digestive fluid is made in your liver and stored in your gallbladder. It contains bile acids and bile salts, which help break down the fats in your food so your gut can absorb them. After your food is digested, the leftover bile is reabsorbed and returned to your liver. 
• Bile acid malabsorption (BAM): BAM is also known as bile acid diarrhoea. It happens when your gut can’t properly reabsorb bile or you produce too much. The bile then travels to your large intestine, triggering your gut to contract and draw in water. These factors result in diarrhoea, and the bile in your poo makes it yellow.
• Steatorrhoea: When there’s too much fat in your poo, it can become yellow, greasy and unusually smelly. This can stem from a lack of bile acid or a problem with the digestive enzymes that break down fat. Steatorrhoea can result from exocrine pancreatic insufficiency (EPI), and this is caused by health conditions such as chronic pancreatitis and untreated coeliac disease. 

Now that we have these medical terms in mind, let’s look at the range of possible causes of yellow poo. 

1. Food supplements

Curcumin is the anti-inflammatory pigment that gives the spice turmeric its vibrant yellow colour. Studies have shown that taking curcumin supplements can turn your poo yellow.

Although curcumin is generally safe, people occasionally have diarrhoea after taking it as a supplement, especially at a high dosage. 

Beta-carotene is another plant pigment available as a supplement that may turn your poo yellow or orange.

2. What you eat

Beta-carotene is in many orange, yellow and green plants, such as carrots, butternut squash and sweet potatoes. You’d have to eat a lot of these to have yellow or orange poo, but it is possible.

Turmeric might also turn your poo yellow if you eat enough of it. Some curries contain turmeric and lots of chilli, and together, these ingredients could cause yellow diarrhoea. 

Meanwhile, eating too many fatty foods can cause steatorrhoea, which can make your poo yellow and greasy.

Foods that contain yellow dyes can also turn your poo this colour. 

3. Giardiasis

Bright yellow diarrhoea can be a symptom of a tummy bug called giardiasis, which can cause steatorrhoea.

You can get giardiasis from eating or drinking contaminated food or water, and from swimming in contaminated lakes or rivers.

4. SIBO

Small intestinal bacterial overgrowth (SIBO) means that you have too many bacteria in your small intestine, the upper part of your gut.

It can cause fat malabsorption and BAM, both of which can make your poo yellow. 

5. IBS

Irritable bowel syndrome (IBS) is a common, long-term condition that causes a range of digestive issues. There are different types of IBS, which cause different symptoms. 

BAM can be a symptom of IBS-D, the type that causes diarrhoea. BAM-associated diarrhoea affects around a quarter of people with IBS-D.

6. Coeliac disease

If you have coeliac disease, consuming gluten damages the lining of your small intestine. Gluten is a protein in grains such as wheat, barley and rye. 

The damage can lead to both steatorrhoea and BAM, each of which can cause yellow diarrhoea.

7. IBDs

These inflammatory bowel conditions are types of autoimmune disease – they cause the immune system to attack the gut.

BAM often results from an IBD called Crohn's disease, and it’s particularly common in people who have Crohn's ileitis and a procedure called ileal resection. 

BAM can also occur if you have ulcerative colitis or microscopic colitis. 

8. Pancreatic conditions

Your pancreas produces digestive enzymes, including lipase (which breaks down fat), protease (which breaks down proteins) and amylase (which breaks down carbohydrates). 

People with pancreatic conditions often have EPI, one cause of steatorrhoea, which can make your poo yellow and greasy.

Some pancreatic conditions that can involve EPI include acute or chronic pancreatitis, type 1 diabetes, pancreatic cancer and cystic fibrosis. Surgery on your pancreas can also cause it.

9. Liver and gallbladder issues

The liver produces bile acids, and the gallbladder stores and releases them.

Pale yellow poo can be a sign that your body isn’t producing enough bile acids, or that you have a blocked bile duct. 

BAM, a cause of yellow diarrhoea, can also develop when you’ve had your gallbladder removed.

10. Orlistat

Orlistat is a weight loss drug that causes you to absorb less fat from food. It’s available with a prescription or over the counter from a pharmacist.

The most common side effects include steatorrhoea and diarrhoea.

The rainbow of poo

Yellow isn’t the only colour that you may spot in the toilet. Here’s what other poo colours, including orange, could mean:

• Brown: If your poo is brown, and you don’t have any digestive symptoms, it’s a sign that your gut is generally healthy. The colour stems from a substance called bilirubin. It’s produced when your liver breaks down red blood cells and bile. 
• Black: Black poo can be due to iron supplements or medicines containing the chemical bismuth, as well as foods like liquorice and squid ink. But unusually smelly black poo with the consistency of tar can indicate a serious health condition, so you should receive medical advice.
• Grey: Iron supplements or bismuth can also turn your poo grey. But pale or grey poo can also signal problems with your pancreas or liver. These issues can stop the release of bile, reducing the pigment in your poo. 
• Green: Green poo can result from eating lots of green vegetables or green food dye. Certain gut infections can also cause green poo. And if you have liver or gallbladder disease, extra bile in your poo (BAM) can make it green.
• Red: Eating beetroot or red food colouring can turn your poo red. But red or dark red poo can also result from bleeding due to conditions such as IBD or severe food poisoning. Blood coating the outside of your poo can point to piles or anal fissures.
• Orange: Supplements containing high levels of beta-carotene – the pigment in carrots, for example – can make your poo orange. Orange poo can also result from extra pigmentation due to BAM.

Also, certain medications can change the colour of your poo. If you suspect that this is happening, speak with your doctor before you consider stopping the treatment. 

And if you’re experiencing other symptoms, such as vomiting, nausea, pain or a fever, it’s important to consult your doctor. 

What to know about diarrhoea

Diarrhoea happens when too much liquid is drawn into your gut. When your poo is watery, it  passes through you more quickly. This means that there isn’t time for your gut to absorb all the nutrients from your food.

One of the main causes of sudden, short-term diarrhoea is a tummy bug – an infection in your gut. This usually results from contact with a person who has the infection or from contaminated food or water.

You can reduce the risk by washing your hands after going to the toilet and before eating. If you’re in places where food or water could be contaminated, drink bottled water and avoid ice cubes, raw salad or fruit, and shellfish.

Diarrhoea can also result from stress or a food intolerance. And people with IBS may get it when they eat FODMAPs, which are fermentable carbohydrates that draw water into the gut.

Also, people sometimes get diarrhoea while they’re taking antibiotics. Antibiotic-associated diarrhoea affects up to 25% of people. It will stop once you finish your course of antibiotics.

It's important to take the full course that your doctor has prescribed. But contact them if you're experiencing diarrhoea. And make sure to drink plenty of liquids to replace the water you’ve lost.

How to treat yellow diarrhoea at home

Whether you have short-term diarrhoea from an infection, or recurring diarrhoea linked to stress or your diet, there are steps you can take at home to help.

• Ask about medication: Over-the-counter medicines like loperamide (sold as Imodium) help slow your digestion, reducing diarrhoea. Your doctor may prescribe it if you have IBS or Crohn’s disease, both of which can cause yellow diarrhoea.
• Consider probiotics: These are live bacteria that can benefit your gut health. There’s evidence that certain probiotic supplements can reduce diarrhoea caused by tummy bugs and antibiotics. They may also help improve longer-term symptoms of IBS-D. If you decide to try probiotics, the NHS recommends taking them for at least 4 weeks to see if they work.
• Manage stress: Direct links between your gut and brain mean that stress and anxiety can cause diarrhoea. To manage this, try meditation or breathing exercises, physical activity (like yoga, pilates or walking) or a talking therapy, such as cognitive behavioural therapy (CBT). And speak with your doctor if you’re concerned about your stress levels. 
• Rehydrate: Diarrhoea leads to a loss of water and salts, causing dehydration. To stay hydrated, drink plenty of liquids, eat soups or take an oral rehydration solution from the pharmacy. Starchy foods, like pasta, rice or crackers, can also help your body absorb fluid and salts. 
• Limit fatty foods: Eating high-fat foods can lead to steatorrhoea for people with certain underlying conditions. If you have IBS with diarrhoea, for example, limiting fatty foods may ease your symptoms.
• Reduce spice: Some curries contain both hot chilli peppers, which can cause diarrhoea, and turmeric, which can make poo yellow. If you think chilli is causing your diarrhoea, opt for herbs and other spices instead. 
• Keep a food and symptom diary: If you regularly have diarrhoea after meals, tracking your diet and symptoms can help you identify triggering foods. If your doctor thinks you have a food intolerance, they may suggest a low-FODMAP diet.

When to see a doctor

Everyone gets diarrhoea from time to time. Although it’s not much fun, it’s usually nothing to worry about and will clear up within 1 week.

But you should consult a doctor if you have diarrhoea and:

• It’s severe or very frequent.
• It lasts longer than 1 week. 
• There’s blood in it. 
• You’re vomiting and can’t keep liquids down.
• You have a bad or continuous stomach-ache. 
• You’re losing weight.
• Your diarrhoea happens at night.
• You’ve recently been treated in hospital.
• You have signs of dehydration, like feeling drowsy or dizzy, or weeing less than usual.
• Your poo is black or dark. 

Summary

Many different factors can turn your poo yellow.

Some are relatively harmless, while others are health conditions that can be serious. These may cause unused bile or undigested fat to go into your poo.

Possible causes of yellow poo include:

• food supplements, like curcumin or beta-carotene
• yellow foods or dyes
• too much fat in meals when you have malabsorption (BAM)
• the gut infection giardiasis
• SIBO, an overgrowth of bacteria
• IBS
• coeliac disease
• IBDs, such as Crohn’s
• problems with your pancreas
• conditions affecting your liver or gallbladder
• the weight loss drug orlistat

If you have diarrhoea, it’s important to stay hydrated. And if diarrhoea is severe or lasts more than 1 week, it’s a good idea to speak with your doctor.

To learn more about other gut health topics, visit Symprove’s Gut Hub. 

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