What is Metamucil (psyllium husk) and can it help with IBS- diarrhea?

You may have heard of Metamucil being a popular option to manage diarrhea or constipation.

This article will discuss what Metamucil is, how it works, how it should be taken, possible side effects and alternative stool-bulking agents.

This post is for general information and interest only; it does not provide medical advice. Please seek advice from your doctor. Please note we receive no financial benefit from the brands discussed in the post.

What is Metamucil?

Metamucil is a brand of bulk-forming soluble fibre supplement. The main ingredient in Metamucil is psyllium husk (also known as ispaghula husk) which is made from the husks of the Plantago ovata plant (1).

Metamucil is available over-the-counter in capsule, granule, liquid and powdered forms (7).

Alternative brands of psyllium husk include:

• Fiberall
• Fybogel
• Hydrocil
• Konysl
• Laxmar
• Perdiem Fiber

How does Metamucil work to relieve IBS symptoms?

Psyllium husk in Metamucil is able to soak up and retain water. This action happens in your gut, which can make your stools bulkier and more formed. This means Metamucil can ease both constipation and diarrhea. 

This action can also relieve abdominal pain and discomfort in some people with IBS (2). A study has shown that participants receiving 10g of psyllium per day has led to a significant reduction in the severity of IBS symptoms such as abdominal pain. Bowel bowel habits were also improved in just a week (4).

Interestingly, psyllium’s water-retaining and gel-forming effects play a role in improving your blood sugar and cholesterol levels. A study has shown that adding Metamucil to a normal diet significantly improved cholesterol and insulin levels in people who were overweight or obese (5).

When and how should you take Metamucil?

Metamucil typically takes 2-3 days to work and it should not be taken before bed (8). You should always follow the manufacturer’s instructions on how to take it.

According to the British Society of Gastroenterology guidelines, psyllium effectively treats IBS symptoms. They also advise to begin at a small dose (3 – 4 g/day) and gradually increase to the recommended amount to avoid bloating due to its fibre content (6).

You should always take Metamucil or other psyllium husk supplements with a 240ml glass of water. This is because it relies on the action of water to work properly, and without it, it could even result in choking in extreme cases (9).

If using the powdered form, you can sprinkle Metamucil into soups, sauces, yoghurts, smoothies, cereals or even use it in the place of eggs and flour in baked goods.

Psyllium can decrease or delay the absorption of certain medications, possibly making them less effective. This means that you should take it 2 hours apart from your other medications (10, 11). You should always consult with your doctor or pharmacist.

Are there any side effects of Metamucil?

Common side effects of Metamucil (and psyllium husk in general) can include (12):

• Abdominal pain and cramps
• Bloating
• Changes in bowel habits

You can help reduce these side effects by increasing your dosage gradually. Ensuring to drink plenty of fluids while taking Metamucil can also help ease side effects. Speak to your doctor immediately if any side effects persist or worsen.

There are some other less common side effects, which you can get from the manufacturer’s website.

Alternative stool bulking agents

There are other high-fibre stool bulking agents that can be introduced into your diet, such as:

• Oats
• Beans
• Chia seeds
• Low FODMAP fruits and vegetables

Citrucel (Methylcellulose) is another medication that functions the same as Metamucil due to its psyllium husk content  (16).

An alternative to fibre supplements to manage diarrhea includes antidiarrheal medications. 

You can read more about the management of IBS-D here.

Summary

Metamucil is a fibre supplement containing psyllium husk, which can relieve IBS symptoms, including constipation and diarrhea.

Remember that IBS is multifactorial, so working with a Registered Dietitian can be helpful to figure out which management techniques work for you. 

Written by Leeona Lam MSc, ANutr and reviewed by Beth Willson Specialist Surgical Dietitian BSc Hons RD