If you’re anything like most of my clients you’ve researched all the typical IBS supplements and you might well have seen psyllium husk advertised.
Or it could be recommended by your doctor. This blog post will explain how psyllium husk can be used by people with IBS. And it’s not just for constipation!
What is psyllium husk?
Psyllium husk is derived from the seeds of the Plantago ovata plant. It’s sometimes called Ispaghula, and is in products like Fybogel in the UK, or Metamucil in the US.
Psyllium is used as a dietary fibre supplement for both constipation and diarrhoea predominant IBS. It’s known as a bulk forming laxative because of this added fibre.
What kind of fibre is psyllium husk?
Dietary fibre is broadly classified into two types: soluble and insoluble. Both types of fibre are important for our digestion. They have different effects on our gastrointestinal system.
- Soluble fibre dissolves in water to form a gel-like substance. This type of fibre can slow your digestion. This means it can help regulate blood sugar levels and may lower cholesterol. Soluble fibre is found in foods like oats, beans, apples, and citrus fruits.
- Insoluble fibre on the other hand, does not dissolve in water. It adds bulk to your stool and helps food pass more quickly through the gut. This type of fibre is found in whole grains, nuts, vegetables, and wheat bran.
Psyllium husk is primarily composed of soluble fibre. It contains soluble and insoluble fibre in a ratio of 7:3, so more soluble.
When it’s mixed with water, psyllium forms a viscous gel that can help regulate bowel movements by softening the stool and making it easier to pass, whilst also forming a stool from liquid.
This makes psyllium particularly effective in managing both constipation and diarrhoea.
How soluble fibre can help your IBS
The reason psyllium helps you is down to the soluble fibre. This type of fibre interacts with water during digestion.
- Water absorption – Psyllium absorbs water as it moves through your digestive tract. This absorption increases the volume and moisture content of your poo, making it easier to pass in cases of constipation.
- Stool softening – The gel-like consistency formed by psyllium’s soluble fibre helps soften the stool. This can prevent the hard, dry stools often which you get with constipation. If you get looser stools it can help by adding some form to loose stools.
- Slowing digestion – If you’re someone with super quick transit time then it might help. The gel slows the speedy movement of food through the digestive tract, allowing for better absorption of nutrients and giving the body more time to regulate digestion. This is particularly helpful in stabilizing your blood sugar levels, reducing the urgency and frequency of bowel movements.
- Supporting your gut microbes – Soluble fibre like psyllium can also serve as a prebiotic, promoting the growth of beneficial bacteria in your large intestine. We need a healthy gut microbiome for overall digestive health.
Is psyllium husk fermentable?
The other way we judge fibre, apart from soluble or insoluble, is whether it’s fermented. Fermentation by gut microbes is normally a good thing, but for some people with IBS can cause bloating and excessive gas.
Psyllium husk is only minimally fermentable by your gut bacteria. This means it produces less gas when compared to other types of fibre that are more fully fermented in the colon.
Is psyllium low FODMAP?
There isn’t a FODMAP rating on psyllium husk (as at Sept 24) but it’s thought to be suitable on the low FODMAP diet.
However, some of my clients can still report mild bloating when they start introducing psyllium into their diet. This typically decreases as your digestion adapts.
Psyllium husk is a good source of fibre for Bifidobacteria and these microbes are associated with a healthy regular bowel movement.
What does research say about using psyllium for IBS?
It’s a generally positive picture. In one study 275 patients with confirmed IBS were randomly allocated to a 12 week treatment of 10g psyllium, 10g wheat bran, and a placebo group. After three months of treatment, symptom severity in the psyllium group was reduced by 90 points compared with 49 points in the placebo group.
This means they felt better and had less severe IBS symptoms.
Constipation may be relieved with psyllium
The mechanism for helping you with better bowel movements is likely to be through improved stool water weight, and increasing the bulk of poo.
This change in transit time also altered the bacteria living in the colon of constipated patients in one 7 day trial. The people took 21g (3x 7g) of psyllium each day which is quite a high dose, and it was only for one week.
Psyllium husk can improve diarrhoea
By increasing the volume of stool moving through your gut you might find the overly quick transit time may slow down.
One of the issues with diarrhoea predominant IBS is the urgency, and even incontinence. A randomized, double-blind, placebo-controlled crossover trial study on incontinent men showed using psyllium was as effective as loperamide after 4 weeks. And the group taking the psyllium husk had fewer side effects than those taking the anti-diarrhoea drugs.
How to use psyllium husk if you have IBS
You’ll notice that the dose used in research trials I highlighted above, is often around the 10g of psyllium per day level.
You don’t always need to take this much. I definitely recommend starting low and slow. The British Society of Gastroenterologists suggests starting with 3-4g and working up from there.
Is capsules or powder better for psyllium husk?
You can buy psyllium in capsules or powder. Many of my clients report the powder is easier to control dosage, but can be hard to swallow.
Literally, it’s hard to mix into water, and then can be gloopy! Quite a few people I work with can’t get passed this issue and so prefer capsules.
Remember you’ll need to drink enough water when you increase your fibre levels to avoid getting constipated. Keep your fluid levels to 2 litres per day to avoid this.
Potential side effects of taking psyllium husk
I find psyllium husk well tolerated by my IBS clients, but it doesn’t work for everyone.
Possible adverse effects
Common side effects you could potentially feel include bloating, gas, cramping. This might happen if you don’t drink enough water, so your gut slows right down. Other side effects might include abdominal distension; bronchospasm; conjunctivitis; gastrointestinal disorders; hypersensitivity; rhinitis; skin reactions.
My advice is to start low and slow with any new supplement. Especially if you’re sensitive to new products.
When to be extra cautious with psyllium
NICE guidelines say psyllium should be avoided for anyone with colonic atony; faecal impaction; intestinal obstruction; reduced gut motility; sudden change in bowel habit that has persisted more than two weeks; undiagnosed rectal bleeding.
If you’ve got diabetes and take psyllium after a meal you may find that your blood sugar levels are lower than normal. This means you might need to adjust your insulin medication.
Be careful if you’re on any kind of medication
Psyllium husk may affect absorption of certain drugs. It’s best to take it about an hour or two away from any medication.
In summary
In an ideal world you’d get all your fibre from food, and wouldn’t need to worry about any supplements. But sometimes it can give you a helping hand to get your symptoms under control. Psyllium husk is a good supplement for IBS, and normally well tolerated.
IBS Nutritionist
Hi, I’m Anna Mapson, registered Nutritional Therapist.
I help people with IBS and SIBO get control of unpredictable gut symptoms to find long term relief from painful and embarrassing IBS without restrictive dieting.
I can help you to:
- understand your digestion better, so you recognise your triggers
- eat a well balanced diet, with tasty meals that are simple to prepare
- reintroduce your trigger foods so you can get back to enjoying food again
Find more about my 3 month 1:1 Gut Reset programme.
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July 22, 2026
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1 comment
Paul Robertson
Do you do personal consultation and diet planning? I have what i would call an extreme gas situation. My situation may be a bit unusual. My cell number is 713-705-6783 and I prefer phone to email (my right hand is injured). I look forward to hearing from you.
Ciao
Paul