Metamucil (psyllium) For IBS: In-depth Review (Dr. Farahat)

[simple-author-box] Is Metamucil for IBS effective in relieving your IBS symptoms?  Is Metamucil equally effective in different IBS subtypes (constipation, Diarrhea, and mixed types)? If you are planning to use Metamucil for your IBS, this is an A-Z guide that will answer all your questions about this supplement efficacy, safety, how to use, and side effects. was founded by me, a gastroenterology doctor and IBS sufferer.  I try to help by providing quality evidence-based answers to your IBS questions. Stay tuned

1- The Evidence from studies about Metamucil for IBS.

Metamucil (psyllium) is a type of fiber used to ease your IBS symptoms. Basically, fibers are of two main types:
  • Insoluble fiber: It doesn’t dissolve in water and cannot be digested by your intestinal enzymes. It adds bulk to stool. This type of fiber may hurt your IBS especially if taken in large amounts.
  • Soluble fiber: this type of fiber is soluble in water forming a gel. Also, it is fermented by gut bacteria. The soluble fiber is further divided according to “fermentability” into:
    • Highly fermentable: Especially short-chain fatty acids (FODMAPs), they are BAD for IBS as they produce more gas that hurts your IBS.
    • Moderately fermentable: It doesn’t produce too much gas, so you can obtain the benefits without the side effects. An example is Psyllium (Metamucil).
The role of fiber is still controversial in irritable bowel syndrome. This 2012 meta-analysis found NO benefits for both soluble and insoluble fibers in IBS.  However, another meta-analysis found that the soluble fiber psyllium (Metamucil) was associated with a small improvement in symptoms of IBS compared to placebo. (placebo = fake treatment used in studies to asses the efficacy of the true treatment). Also, other fibers like Bran found not significantly better than placebo in improving IBS. So, this left us with Metamucil to be the best fiber to try for IBS (although the evidence is not very strong). (reference) Metamucil is “Soluble”, “Moderately Fermentable” Fiber that dissolves in water inside your small intestine and colon and produces beneficial effects for your IBS especially with constipation. This video from Metamucil YouTube channel explains exactly how Metamucil works Metamucil for IBS works in different ways to benefit your IBS: (reference)
  • Metamucil Retains water inside your intestine → it swells and makes gelatinous mass → thus makes your stool softer and this helps your IBS, especially IBS with constipation [Laxative effect]
  • Also, this “Mass forming” advantage of Metamucil will increase the bulk of your stool → stimulates peristaltic movement of your colon → helps with easier passage of stool (especially with constipation). (reference)
  • Another believed benefit of Metamucil is it helps the beneficial bacteria (microbiota) inside your colon to function properly → this helps normal stool formation and normal motility of your colon.
  • It is believed that it also augments the immunity of your Gastrointestinal tract.
Metamucil for IBS benefits

Also, you will obtain other health benefits from Metamucil.

Metamucil also has proven health benefits, for people with heart diseases and diabetes. The benefits include:
  • Slows down sugar absorption: Metamucil forms Gel → this gel slows down the process of sugar absorption → Prevents the “gush” of sugar from your intestine into your bloodstream → this protects from fluctuations of blood sugar after meals.
  • Help with cholesterol: Metamucil is used in patients with heart and blood vessel atherosclerotic diseases (especially ischemic heart diseases, hypertension) as it helps in decreasing your blood cholesterol levels.
  • Helps with satiety: Metamucil helps with feeling “full”  for a longer time by forming a bulk inside your intestine.

Metamucil stool changes:

You will notice stool changes after using Metamucil:
  • Stool form changes: Metamucil makes the hard stool softer, by retaining water in the stool. Also, in people with severe IBS-D, the gel-forming ability of Metamucil may help the improvement of the “very loose diarrhea”
  • Stool color changes: you may experience some color changes after using Metamucil because some forms are flavored (as orange flavor)

2- How much Metamucil is effective for IBS?

Metamucil (psyllium) is studied in lots of trials and meta-analysis studies. Psyllium, in particular, showed to be effective with IBS in most trials (compared to other fiber types like bran). This 2008 Meta-analysis concluded that Psyllium has documented effects in the management of IBS symptoms and the improvement of overall IBS symptoms. metamucil for IBS study The same study recommends a dietary fiber supplement containing Metamucil for All IBS subtypes (IBS-Constipation, IBS-Diarrhea, and IBS-Mixed type). metamucil benefits for all types of IBS The effect of Metamucil is not typical for everyone, and it depends on:
  • IBS subtype: best response rates to Metamucil supplementation with IBS-constipation subtype. However, it may benefit other types of IBS including IBS with diarrhea.
  • Different dosing: using higher doses from the start may cause transient days of bloating and abdominal discomfort, so start low and go slow to obtain the best effects.
  • Individual variations: response to Metamucil (Psyllium) is variable for every IBS patients. But regarding its potential benefits, lower cost, and safety we suggest trial with psyllium especially if you have the IBS constipation subtype.

Metamucil and IBS constipation (One of my favorite and most reputable clinical practice guides) recommends a trial of psyllium (Metamucil) for all patients with IBS- constipation subtype. Metamucil dissolves in water forming a gel-like substance that makes the stool softer; so it may help with IBS-constipation.

Does Metamucil help IBS diarrhea?

Although evidence is not strong, some studies recommend Metamucil for the IBS-diarrhea subtype due to gel-forming ability will make the stool less lose in patients with IBS-diarrhea. I usually don’t routinely recommend fibers to IBS-D patients. But it is worth trying to add Metamucil for patients who are still symptomatic despite other anti-diarrhea measures. Some (not all) patients may see results. (reference)

Metamucil and IBS abdominal pain, gas, and bloating

Trials evaluating Metamucil also concluded that Metamucil may improve overall symptoms of IBS including abdominal pain and bloating (reference). But transient abdominal bloating and pain associated with the introduction of Metamucil (especially if taken at larger doses from the start) is reported. These symptoms resolve after continuing Metamucil for longer periods. 

3- When to take Metamucil for IBS?

Don’t take Metamucil unless you consult your doctor. Work with your doctor to decide the best option that fits your IBS type and condition. Use Metamucil especially for constipation-predominant IBS. Also, it can be tried with any other types of IBS after consultation with your doctor. When not to take Metamucil?
  • If you have a sensitivity to Metamucil or any of its components.
  • If you have very severe constipation or suspected intestinal obstruction (persistent vomiting, severe distension, and intolerable abdominal pain).
  • If you have past experience with Metamucil worsening your IBS or making no improvement.

4- Metamucil Quick facts:

  • Metamucil Powder contains 180 teaspoons with a weight of 1.04 Kg (2.3 Ibs).
  • For each teaspoon (5.6 gm), it contains:
    • 15 Kcal (about 0.7% of recommended daily calories)
    • It contains 10% of your total daily needs of dietary fiber (mainly soluble fiber psyllium, but it also contains a small amount of insoluble fiber)
    • Contain small amounts of Iron, sodium, and potassium.
  • Flavored with Stevia (natural, plant-based sweetener). [sugar-free premium blend]
  • Also, it is present in capsule form which also requires you to drink with a large amount of water.

5- Summary of Metamucil dosing:

The dose of Metamucil ranges from 1 teaspoon (5.6gm) of the powder form once daily and may reach up to 2 teaspoons 3 times per day (6 rounded teaspoons daily). The powder is mixed with plenty of water 8 Fl.Oz (250 CC) of water The dose of Metamucil capsules is roughly the same, ranging from one capsule to 6 capsules a day. Consult your doctor if you are planning to take Metamucil for more than 7 days

6- How to take Metamucil for best results for your IBS

Regarding IBS, you have to be cautious about Metamucil dosing, especially if this is the first experience with Metamucil. Always ask your doctor about the perfect dosing for your IBS. Best tips for using Metamucil for IBS: 
  • Start Low: fiber is a double-edged sword for IBS. My most important advice while starting with Metamucil for IBS is to take the smallest dose available (one teaspoon per day/ one capsule per day). Introducing too much fiber from the start can increase gas and bloat and may trigger IBS colics and stool changes.
  • And Go Slow: after experiencing the lowest dose for some period (5-7 days) you can gradually increase the dose (1 teaspoon twice daily) for another 5-7 days. And watch for the side-effects on your IBS symptoms
  •  The Maximum dose is 2 rounded teaspoon (or 1 capsule) three times daily. Only use the maximum dosing if advised by your doctor. 
  • Water is vital: water is essential for Metamucil to work for your IBS. the gel-forming property needs a large amount of water to work; Also, water protects from Metamucil side effects and allergic reactions to the dry powder.
At least add 8 OZs (250 CC) of water to Metamucil powder ( or drink the same amount together with the Metamucil capsule).
  • Stir well: to keep Metamucil from clumping or forming a dry bubble, Or you can add a little amount of water and stir it up well and then add the rest of water and stir again.
  •  No relation to meals: Metamucil can be taken before or after meals. There is no problem as long as you get enough amount of water.
  • The Duration: DON’T take Metamucil for IBS for more than 7 continuous days Unless prescribed by your doctor. You can use it occasionally for constipation attacks, it usually relieves constipation within 12 to 72 hours.
  • Don’t take with other drugs at the same time:  Metamucil may trap and decrease the absorption of the other drugs. Take Metamucil away from other drugs (at least two hours apart).
  • When to discontinue Metamucil: Metamucil may cause some gas and bloat for some IBS sufferers. If you consistently experience gas even with the lowest dose you have to discontinue it.
  • Metamucil doesn’t work alone: to get the best results from Metamucil to use Metamucil together with other strategies to help your IBS like diet, exercise, and other medications as prescribed by your doctor.

7- Side effects of Metamucil for IBS (Can Metamucil makes IBS worse?) (reference)

Metamucil is considered generally safe supplement, the possible side effects include:

A- Gas and bloating (most common)

Starting with a big dose is the most common cause of experiencing discomfort or bloating and gas. Also, Gas and bloating with Metamucil can occur in certain IBS patients even with the lowest doses. Consult your doctor to make the best decision balancing the benefits and side effects of Metamucil for IBS. Bloating is one of the frequently experienced symptoms of IBS. it is not exclusively caused by Metamucil. A common cause is diet and lack of physical activity. Try to fine-tune other factors increasing your gas and bloating before deciding to discontinue Metamucil.

B- Allergic reactions (most dangerous): 

Inhaling Metamucil powder or taking it without water may cause some allergic reactions. Get emergency medical help  If you experience Hives, swelling of your lips, face, throat, tongue or having difficulty breathing. To avoid allergic reactions always mix Metamucil with water and stir well. Also, take smaller doses at the beginning to avoid severe reactions with larger doses.

C- Chocking (difficult swallowing): 

It can occur with the capsule or the powder form. Metamucil powder and capsule can be stuck in your throat or esophagus especially if you don’t take enough water with them To prevent this from happening:
  • Swallow one capsule at a time.
  • Always use plenty of water with the capsule or the powder form.
  • Avoid use if you have oesophageal stricture or any swallowing problems
  • Avoid Metamucil use if you have severe intestinal adhesions or a history of intestinal obstruction.

D- Worsening of IBS symptoms (abdominal pain and stool changes):

Metamucil may induce IBS abdominal pain (cramps) and stool changes (diarrhea or constipation) in some people. Mild diarrhea is more common due to its laxative effects.  It may be due to individual variations or faulty dosing. Work with your doctor to define the best dosing for your condition. And if you continue to experience worsening of IBS symptoms, discontinuation of Metamucil is an option. Also, a small number of users reported rectal pain with Metamucil use for IBS.

E- Nausea:

Some patients may experience nausea, especially with higher doses. Lowering your dose may help the improvement of nausea.

8- Metamucil safety in pregnant and lactating IBS patients. (reference)


No reported animal or controlled human studies for the use of psyllium (Metamucil) in human studies. Also, there is no formal FDA pregnancy category for Psyllium.  However, Psyllium is not absorbed into the circulation from your intestine and this is theoretically safe. But regarding different formulations and additives to Metamucil, don’t use Metamucil for IBS in pregnancy unless prescribed by your doctor.


Also, few data are available about its use during lactation. However, its use is considered acceptable owing to the fact that it is not absorbed into the bloodstream (and consequently not excreted into breastmilk. 

9- Pricing & How to find Metamucil for IBS?

You can find Metamucil for IBS in your local store or pharmacy. Also, you can purchase it online from and other online retailers (check our resources page for links)

Take-home Messages:

  • Research has found some evidence that Metamucil (Psyllium) may benefit your IBS.
  • Metamucil works for IBS by forming a soluble gel-like mass that traps water and improves stool consistency.
  • Metamucil is originally laxatives, best results achieved when used with IBS-constipation. But evidence exists that it may help with other types of irritable bowel syndrome.
  • Commonly, Metamucil for IBS may cause some bloating and gas, especially if taken in larger doses.
  • Always start with smaller doses and increase it gradually. Consult your doctor if you are planning to take it for longer than a week.
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