Can You Use Metamucil For IBS With Diarrhea?

In our latest question and answer, the pharmacist discusses use of Metamucil for irritable bowel syndrome (IBS) that is diarrhea predominant.

Can You Use Metamucil For IBS With Diarrhea?
May 09, 2018

Granny asked

I have had IBS for years with diarrhea. It was suggested I take Metamucil. I am a little hesitant to take it thinking it may make the diarrhea even worse. What is your opinion?


Metamucil IBS-DIrritable bowel syndrome (IBS) is one of the most commonly diagnosed gastrointestinal disorder according to studies, affecting more than 10% of the population. Common symptoms of IBS include:

  • Bloating
  • Lower abdominal pain
  • Diarrhea or constipation

IBS is commonly classified as either constipation predominant (IBS-C) or diarrhea predominant (IBS-D) and depending on which you are diagnosed with will determine appropriate treatment options.

For first line treatment of IBS, most guidelines begin by recommending to stress and foods that worsen symptoms such as certain types of carbohydrates (e.g. "Di" and" mono" saccharides) that ferment in the GI tract and other substances like caffeine, lactose, or artificial sweeteners.

Metamucil Fiber For IBS-D

Studies suggest that soluble fiber, such as Metamucil (psyllium), can help relieve symptoms of IBS-D such as:

  • Abdominal pain
  • Stool consistency

Metamucil works by absorbing liquid in the gastrointestinal tract, causing an expansion of the stool, which stimulates peristalsis and bowel movement. It may be a good non-pharmacologic treatment for many individuals. It is important to note though that some studies have reported that Metamucil type fiber supplements can exacerbate symptoms in some patients and therefore should be used under the supervision of your doctor.

It is important to note that the type of fiber that is recommended for IBS-D is soluble fiber such as psyllium (Metamucil), not insoluble fiber, like bran, which can often increase cramping and bloating in IBS patients.

One recommended dosing strategy for fiber is to start with one tablespoonful of soluble fiber (like Metamucil) with one meal daily, and dosing gradually to include fiber with two or three meals daily.

As mentioned, soluble fibers can often be a good initial, non-pharmacologic treatment option for IBS patients if advised by your doctor. However, depending on the severity of symptoms of your IBS-D, other drug options may be needed such as Imodium (loperamide), Lotronex (alosetron), Xifaxan (rifaximin) or Viberzi (eluxadoline).

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