Antidiarrhoeals and inflammatory bowel disease

Antidiarrhoeals are used to treat diarrhoea. Anyone can have diarrhoea, but it's particularly common in people with Crohn's disease and ulcerative colitis. Find out more about using this medication when you have IBD...


Antidiarrhoeals are a type of medicine used to treat diarrhoea (frequent loose, watery stools (poo), perhaps accompanied with uncontrollable urgency).

Anyone can have diarrhoea, but diarrhoea is particularly common in people with inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis.

Some of the common, non-IBD things that can cause diarrhoea in anyone include: 

  • Infections caused by bacteria and viruses, such as gastroenteritis 
  • Diet, food allergies and intolerances
  • Functional gut disorders, such as irritable bowel syndrome (IBS)
  • Side effects from some medicines, such as antibiotics
  • Stress and anxiety

In these cases diarrhoea will often only last a short time and will clear up after a few days without treatment, although some people choose to take antidiarrhoeal medication to help them manage the symptoms during this time. Some antidiarrhoeal medicines can be bought over-the-counter without a prescription, while others are only available on prescription from a doctor. They only treat the symptom, not the cause of the diarrhoea and if it doesn’t go away within a few days you should speak to a doctor.

Why might I need antidiarrhoeals in inflammatory bowel disease?

Chronic diarrhoea is a common symptom of inflammatory bowel disease (IBD) and it’s particularly important that you understand more about the reason for your diarrhoea before you start taking antidiarrhoeal medication without talking your IBD team.

There are a variety of reasons why you might have diarrhoea if you have IBD (as well as all the reasons listed earlier which may not be directly related to your IBD). 

Inflammation - When you are having a flare, the inside of your colon can become inflamed and ulcerated, making it difficult for water to be absorbed from digested food passing through. This can lead to frequent and often urgent diarrhoea. 

Medicines - IBD medicines such as 5-ASAs and some immunosuppressants, or other medicines and supplements that you take to treat the symptoms of IBD can cause side effects including diarrhoea. Iron supplements are commonly prescribed in IBD, and can have side effects of both constipation and/or diarrhoea.

Surgery - Surgery for IBD to remove your colon can cause diarrhoea, as water can no longer be absorbed in your colon from your digested food once it has been removed.

Bile salt diarrhoea (bile acid malabsorption) - Your liver produces bile salts to help with digestion, which are usually reabsorbed in your ileum (the last part of your small intestine). If your ileum is inflamed, or has been removed, higher levels of bile salts continue into your colon (large bowel). Your body then sends more water to your colon, causing diarrhoea. This is known as bile salt diarrhoea or bile acid malabsorption.

Diet and food sensitivities - Some people with IBD find that certain foods or food types, such as gluten and dairy, can trigger symptoms like diarrhoea, or make them worse. 

IBS - When you have IBD you can still experience symptoms even when there is little or no evidence of inflammation in your gut. These IBS-like symptoms can include diarrhoea.

It is important you speak to your IBD team before taking any antidiarrhoeal medicines. Diarrhoea is a symptom that can indicate a change in disease activity, which may require investigation or a change in your IBD treatment. Antidiarrhoeals simply mask the symptom of diarrhoea, rather than treating the cause and should not be a replacement for your IBD treatment. Taking anti-diarrhoea medication when you have IBD without seeking medical advice could be dangerous. It is also important to make sure the antidiarrhoeal is suitable for you, and won’t interact with other medicines you are taking. 

If you have narrowing of the bowel (stricture) antidiarrhoeals may not be suitable for you.

Toxic megacolon is a rare but very serious complication that can happen in people with IBD, more commonly in ulcerative colitis. It can happen spontaneously, but it can also be caused by use of certain types of medicines, including antidiarrhoeals.

What type of antidiarrhoeals are there?

There are a few different types of antidiarrhoeal medicines and they each work in different ways.

Antimotility medicines (sometimes called antiperistaltic agents)

Antimotility antidiarrhoeals are opiates and work by slowing down intestinal muscle contractions, and therefore the motility (movement) of your gut. This reduces the speed your digested food travels through your gut, allowing more water to be absorbed back into your body. This means you have more formed poo and need to go less often. Opiate medicines are generally not intended for long-term use as they can cause dependency and addiction. 

Loperamide is a commonly used antimotility antidiarrhoeal. It is available as tablets, capsules and liquids, and can be bought over-the-counter, or prescribed. Brands include:

  • Imodium
  • Dioraleze

Sometimes loperamide is combined with an anti-foaming agent used to treat excess gas called simethicone. 

Unlike other opiates, loperamide does not cross the blood-brain barrier and therefore does not relieve pain, and is less likely to cause dependency or addiction.

Diphenoxylate works in a similar way to loperamide, by slowing the motility of your gut. It is often combined with a medicine called atropine which is an antispasmodic, meaning it reduces muscle spasms within the gut. Brands include:

  • Lomotil
  • Lomocot

Codeine is also used to treat diarrhoea but along with diphenoxylate, long-term use can result in dependency and addiction and so may not be suitable to be used for chronic diarrhoea.

Side effects of antimotility medicines include:

  • Abdominal pain
  • Dry mouth
  • Drowsiness
  • Dizziness
  • Constipation 
  • Nausea and vomiting 

If you experience some of these side effects, you may need to avoid driving whilst taking these medicines.

Antisecretory medicines

Less commonly used in the UK than antimotility medicines, antisecretory antidiarrhoeals work by reducing the amount of water entering your bowels, meaning your poo contains less liquid and can pass more slowly through your bowel. They are designed to be used alongside rehydration treatment. 

Racecadotril, known by brand name Hidrasec, reduces the amount of watery secretions that are produced by your intestines. This helps to make your poo less liquid, and also reduces the amount of fluid your body loses. 

Side effects with racecadotril are uncommon, however you may experience skin reaction or rashes. You can find more information in the patient information leaflet.

Adsorbent medicines

Adsorbent anti-diarrhoea medicines are thought to work by binding to toxic chemicals produced by bacteria which trigger inflammation, causing your small intestine to secrete excess fluid. 

Types of adsorbent antidiarrhoeals include:

  • Kaolin
  • Pectin
  • Bismuth subsalicylate 

Bismuth Subsalicylate

Bismuth subsalicylate is a commonly used over-the-counter antidiarrhoeal medicine available as chewable tablets, capsules or liquid medicine. It is also used to treat indigestion, upset stomach and nausea. Brands include:

  • Pepto-Bismol
  • Kaopectate

Bismuth salicylate can temporarily turn your tongue and your poo black, although this side effect will usually go away after stopping taking it.

Bile salt binders

If you have bile salt malabsorption resulting in diarrhoea, you might take bile salt binders. They work by absorbing the overflow bile salts before they reach your colon and cause diarrhoea. They can also interfere with the absorption of other medicines, so it is important to speak to your IBD team before taking them. Types of bile salt drugs include:

  • Cholestyramine (Questran, Prevalite) comes as a powder which you mix with water and drink
  • Colestipol (Colestid) comes as a powder or granules
  • Cholesvalam (Cholestagel) comes as tablets

Some people become constipated when taking these medicines, so you might need to adjust your dose to find the right one for you. Side effects can include indigestion, nausea, tummy pain and bloating.

Interactions between antidiarrhoeals and other medicines 

Taking antidiarrhoeals at the same time as other medicines can affect how they work, or increase the risk of side effects. These medicines include:

  • Antibiotics
  • HIV antiviral medicines
  • Some pain medicines
  • Blood thinning medicines
  • Medicines for gout and arthritis

Always speak to your doctor or IBD team before taking any kind of antidiarrhoeal medicine.

Funding to help in the production of this article was received from PredictSURE IBD, however they had no input into its content.

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