Is your IBS actually Bile Acid Diarrhoea (BAD/BSD)?

Up to 30% of people diagnosed with diarrhoea-predominant IBS (IBS-D) may also have BAD, or a degree of BAD contributing to their symptoms. 

For those with BAD, a daily medication might significantly help their symptoms. 

You may now be wondering if you fall into this category. So here’s what you need to know…

What is Bile Acid Diarrhoea?

Bile salts or bile acids are produced in your liver and they help with the digestion and absorption of fats in your small intestine.

Bile acid are stored in your gallbladder and released into your small intestine when you eat. When bile salts reach the last part of your small intestine – the terminal ileum – they should be reabsorbed into the bloodstream and recycled back to your liver. 

However, some people can experience an imbalance of bile acids within their gut. When bile acids are not fully absorbed in the small intestine or if too much bile acid is produced, more will reach the colon (the large intestine).  When this happens, the bile acids in the colon will cause fluid to be drawn into the colon. This can lead to ‘bile acid diarrhoea’ (BAD), also known as bile acid malabsorption.

What are The Symptoms of Bile Acid Diarrhoea?

  • Bowel frequency
  • Bowel urgency, particularly after eating a rich meal or something fatty
  • Pale or yellow diarrhoea (this can also have other causes and should always be mentioned to your GP/ family doctor)
  • Incontinence (occasionally if the stools are very loose or urgent)
  • Excessive wind
  • Abdominal pain
  • Sometimes diarrhoea can occur at night particularly if you’ve eaten a rich meal in the evening. ** This is very uncommon in pure IBS. If you’ve been diagnosed with IBS-D and diarrhoea is waking you at night, a diagnosis of BAD should be considered

Do these symptoms sound familiar? The symptoms of BAD are very similar to those of IBS-D, no wonder there is so much confusion between the two.

What are the Risk Factors for having Bile Acid Diarrhoea?

  • Anyone with long-standing diarrhoea predominant symptoms could have a degree of BAD that has not been diagnosed
  • Those with IBS-D may also have BAD, or a degree of BAD contributing to their symptoms
  • If you’ve had your gallbladder removed
  • If you’ve had surgery on your small intestine
  • If you have Crohn’s disease of the small intestine, it may be contributing to your symptoms (of course it’s always important to check that your Crohn’s disease activity is under control too)
  • Many people have idiopathic or primary bile acid diarrhoea which means there is no obvious cause

BAD effects between 1-5 in 100 people, so it’s pretty common.

How to Diagnose Bile Acid Diarrhoea?

There are some specialised tests available (one is called a SeHCAT), but these are not widely available.

In many cases, a trial of a bile acid binder medication (often called a ‘bile-mop’) will enable a diagnosis. If BAD is contributing to your symptoms, you will see a marked and rapid improvement once these medications are started.

What's the Treatment for Bile Acid Diarrhoea?

The good news is that BAD can be easily treated with a ‘bile mop’ medication, also known as a bile acid binder (such as cholestyramine or colesevelam). These medications can work wonders and significantly improve your quality of life.

These medications usually work very quickly (within a few days), but it can take a little tweaking to get the dosing right. Occasionally, it may take up to 10 days to see an improvement in symptoms.

A low-fat diet (40g of fat a day) is also a treatment option for some people with BAD. However, this diet should only be trailed under the supervision of a dietitian.

Other natural remedies for BAD are not effective. You are better off sticking to the treatments above for effective results.

Does Bile Acid Diarrhoea affect Nutritional Status?

Vitamin B12 is also absorbed in the terminal ileum. If this part of your bowel is not working properly you may also be at risk of B12 deficiency. 

Bile acid binders can lead to low levels of fat-soluble vitamins (A, D, E, and K) as they interfere with how these vitamins are absorbed. 

If you have BAD speak to your doctor about having your vitamin B12, A, D, E, and K levels tested.

What to Do if you Think you Have Bile Acid Diarrhoea

A diagnosis of BAD may seem daunting. However, a proper diagnosis of BAD and a prescription for the correct medication will greatly improve your quality of life.

If you think that you may be suffering from BAD please contact your GP/family doctor.


Farrugia A, Arasaradnam RBile acid diarrhoea: pathophysiology, diagnosis, and management frontline Gastroenterology 2021;12:500-507

Imran Aziz, Saqib Mumtaz, Hassan Bholah, Fahmid U. Chowdhury, David S. Sanders, Alexander C. Ford. High Prevalence of Idiopathic Bile Acid Diarrhea Among Patients With Diarrhea-Predominant Irritable Bowel Syndrome Based on Rome III Criteria, Clinical Gastroenterology, and Hepatology, Volume 13, Issue 9, 2015,

Mohamed G. Shiha, Zohaib Ashgar, Ellen M. Fraser, Matthew Kurien, Imran Aziz, High prevalence of primary bile acid diarrhoea in patients with functional diarrhoea and irritable bowel syndrome-diarrhoea, based on Rome III and Rome IV criteria, EClinicalMedicine, Volume 25, 2020,

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