Do probiotics help with IBS? What the research shows

Irritable bowel syndrome (IBS) is a long-term condition that affects the gut. Symptoms include abdominal pain linked to changes in bowel habits, bloating, and altered stool frequency or consistency. Diarrhoea, cramps and constipation can also occur. Certain lifestyle changes and medicines can ease symptoms, but no single treatment works for everyone.

Some evidence suggests that certain probiotics can ease symptoms of IBS, at least for some people. So, in this article, we’ll look at the evidence. 

Whether probiotics can help treat IBS isn’t clear-cut, and the evidence is mixed. There are several reasons for this. For instance, studies often test different probiotic strains, alone or in combination. Also, doses can vary, and scientists use different measures of success, such as quality of life or symptom severity.  Let’s explore the research to date.

Do probiotics help with IBS?

While the evidence is mixed, some probiotics may improve some IBS symptoms for some people.

However, the evidence so far doesn’t support the idea that probiotics are effective for all people with IBS. 

Below, we’ll mostly focus on reviews and meta-analyses, which combine data from multiple studies to produce the most reliable answers to scientific questions.

2023 systematic review and meta-analysis

This review, published in the journal Gastroenterology, combined data from 82 studies, involving more than 10,000 participants. 

Overall, the authors conclude that ‘Some combinations of probiotics or strains may be beneficial in IBS. However, certainty in the evidence [...] was low to very low’.

Specifically, they found that there was: 

• moderate certainty in the evidence for the beneficial effects of Escherichia strains

• low certainty for Lactobacillus strains and L. plantarum 299V 

• low certainty of evidence for the combination probiotics they investigated

2022 systematic review and network meta-analysis 

In this review, published in Frontiers in Cellular and Infection Microbiology, the scientists focused solely on randomised controlled trials (RCTs). These studies are considered the gold standard for investigating the effects of a treatment or intervention.

In total, they reanalysed 43 RCTs, including data from more than 5,500 people, and concluded that:

• Bacillus coagulans ranked as the most favourable probiotic for relieving symptoms of IBS in this particular analysis.

• B. coagulans performed better than combinations of probiotics.

• L. plantarum best improved quality of life for people with IBS.

The authors write: ‘B. coagulans had prominent efficacy in treating IBS patients, and incorporating B. coagulans into a probiotic combination, or genetically engineering it to amplify its biological function, may be a future research target to treat IBS patients’.

However, they also explain that because the individual studies vary significantly in their design, diagnosis criteria, population, duration and IBS subtypes, it was ‘difficult to draw robust conclusions’.

2023 systematic review and three-level meta-analysis

This study included data from 72 RCTs. A three-level meta-analysis combines multiple studies with different types of results to help remove some of the biases.

The researchers concluded that there was a ‘better overall effect of probiotics than placebo on the [total] IBS symptoms’, with a medium effect size.

Bacillus probiotics again performed best. Surprisingly, though, shorter durations seemed more effective than longer treatments. The researchers explain that this might be a consequence of the analysis and study types, rather than a true effect.

2024 systematic review and meta-analysis

Published in Clinical Nutrition ESPEN, this study collated data from 20 studies, involving more than 3,000 participants. 

The authors conclude that ‘probiotics are more effective than placebo in reducing global IBS symptoms improvement rate [...] and quality of life scores’. They also write that higher doses and multiple probiotic strains seem to perform best.

However, they couldn’t reach ‘definite conclusions’ because the individual studies used very different approaches, including different durations, participant types, and probiotic strains and doses.

2026 review and meta-analysis

In this review, published in the Journal of Clinical Medicine, researchers compared probiotic strains. In particular, they focused on existing meta-analyses and RCTs that used placebos.

Their analysis included data from 32 studies, which evaluated 10 probiotic strains. Overall, the scientists concluded that these strains improved IBS symptoms:

• Bifidobacterium longum 35624

• L. rhamnosus GG

• Lactiplantibacillus plantarum 299v (DSM 9843)

• Saccharomyces cerevisiae CNCM I-3856

• B. coagulans Unique IS2

The researchers outline a number of limitations. For instance, they had to exclude some probiotic strains because they only featured in one RCT. This, they explain, might bias the data, as only the most commonly used probiotics were included.

Probiotics and IBS: Evidence combined

Although we’ve outlined just five reviews and meta-analyses, it’s already clear why drawing solid conclusions about the effectiveness of probiotics in IBS is challenging.

Overall, though, they conclude that some probiotics can relieve symptoms for some people. But which strains work best, and for how long, is still up for debate.

Next, let’s look at probiotics’ potential to improve specific symptoms of IBS.

What IBS symptoms have probiotics been studied for?

Some studies look at how probiotics affect overall IBS symptom severity. Other studies also investigate whether probiotics help with some IBS symptoms more than others.

This is important because certain strains might affect different symptoms in different ways. For instance, one might relieve abdominal pain only, while another might only relieve bloating.

Next, we’ll look at the evidence for abdominal pain, bloating and distension, and bowel changes like stool consistency.

Abdominal pain in IBS vs. probiotics 

Abdominal pain is a common IBS symptom, and some evidence suggests that certain probiotics may relieve it for some people.

An RCT published in 2020 recruited 330 adults. For 6 weeks, they took 1 of 3 interventions:

• L. acidophilus DDS-1

• B. animalis subsp. lactis UABla-12

• a placebo 

Compared with the placebo, both probiotics significantly reduced abdominal pain.

However, a 2023 review and meta-analysis found that for abdominal pain, ‘there was low certainty in the evidence for a benefit of S. cerevisiae I-3856 and Bifidobacterium strains, and very low certainty for combination probiotics, Lactobacillus, Saccharomyces, and Bacillus strains’.

On the other hand, a 2022 review concluded that B. coagulans significantly improved abdominal pain, and a 2023 review also found that probiotics improved this symptom significantly more than a placebo. 

Probiotics vs. IBS bloating and distension

Abdominal distension and bloating are closely linked terms, but with subtly different meanings. Abdominal distension describes the measurable increase in abdomen size, while bloating describes how abdominal distension feels.

In the 2020 RCT on 330 adults, the scientists also noted that both L. acidophilus DDS-1 and B. animalis subsp. lactis UABla-12 reduced abdominal distension.

By contrast, a 2023 review and meta-analysis concluded that ‘for abdominal bloating or distension there was very low certainty in the evidence for a benefit of combination probiotics and Bacillus strains’. Meanwhile, a 2022 review concluded that B. coagulans significantly reduced bloating.

An RCT from 2005 confirms how confusing it can be to look at individual symptoms. The researchers found that compared with a placebo, a probiotic combination called VSL#3 significantly reduced flatulence, but made no difference to bloating, bowel changes and abdominal pain.

IBS bowel changes and probiotics

Another common feature of IBS is changes to stool consistency and frequency. Some people commonly experience diarrhoea, others constipation and some both.

The same 2020 RCT also found that both probiotic interventions tested were associated with improvements in bowel consistency.

An RCT published in 2024 found that, compared with a placebo, the probiotic strain B. lactis BLa80 significantly improved stool frequency in people with IBS who were often constipated. But surprisingly, the probiotic didn’t improve stool consistency. 

Why do studies of probiotics for IBS reach different conclusions?

As we've seen, studies of probiotics for IBS are hard to compare, and they sometimes contradict each other. There are several reasons, for instance:

• Studies often test different probiotic strains or combinations of strains.

• The dose and length of treatments can differ.

• Studies may include different groups of people, such as older adults, teenagers or people with other health conditions.

• Not all studies take into account the subtypes of IBS (more about this later on).

• Researchers may measure different symptoms or define improvement using measures of overall symptom severity or quality of life. 

• Some studies are larger or better designed than others.

• Studies on IBS typically have quite a large placebo response, which makes results difficult to interpret.

Does the probiotic strain matter for IBS?

It’s easy to imagine that friendly bacteria are all doing similar things, but that’s not the case.

Recognising the species used in a study isn’t enough – you need to know the strain, too. Here’s an example:

• Species name: L. acidophilus 

• Strain name: L. acidophilus DDS-1

Even if two strains are closely related, they can have quite different effects in your gut. So, if a study supports the benefits of L. acidophilus DDS-1, it doesn’t mean that a probiotic containing any other strain of L. acidophilus will have the same effect.

In IBS probiotic research, scientists sometimes use more than one bacterial strain in the same intervention, and this adds complexity. If any benefits are measured, one strain may be doing most of the work, while the others do nothing, for instance.

Also, some bacteria interact, and this influences how well they survive – for better or worse.

Here’s one example of how this can work: B. bifidum PRL2010 breaks down complex carbohydrates into compounds that B. breve UCC2003 can feed on. So, without B. bifidum PRL2010 being present, B. breve UCC2003 might struggle to thrive.

Here’s an even more relevant example: A 2024 RCT recruited 65 people with IBS who regularly experienced diarrhoea. They were split into three groups:

• a placebo

• L. reuteri ATCC PTA 6475 alone

• L. reuteri ATCC PTA 6475 plus L. reuteri DSM 17938

Although both of the probiotic groups experienced improved symptoms, compared with the placebo group, the benefits were only statistically significant for those who took both strains together.

Does the type of IBS make a difference?

Broadly speaking, there are three forms of IBS:

• IBS with constipation (IBS-C): More likely to experience constipation than diarrhoea

• IBS with diarrhoea (IBS-D): More likely to experience diarrhoea than constipation

• IBS with mixed bowel habits (IBS-M): A mix of diarrhoea and constipation

There’s a lack of probiotic research involving IBS-C and IBS-M. Much of it has focused on IBS-D. As we've seen, the evidence for using probiotics to treat IBS is somewhat mixed, so much more research is needed to know which probiotics best suit each subtype.

What do clinical guidelines say about probiotics for IBS?

Mirroring the mixed evidence, each professional body has a different take on probiotics and their use in treating IBS.

National Institute for Health and Care Excellence

The NICE guidelines for diagnosing and managing IBS recommend:

‘People with IBS who choose to try probiotics should be advised to take the product for at least 4 weeks while monitoring the effect. Probiotics should be taken at the dose recommended by the manufacturer.’

American College of Gastroenterology

The ACG clinical guidelines for managing IBS state:

‘We suggest against probiotics for the treatment of global IBS symptoms.’ This, they explain, is due to the lack of compelling evidence and mixed results.

However, they also note that ‘the use of probiotics in the treatment of IBS is an important area of research, given the importance of the intestinal microbiome in this condition’.

American Gastroenterological Association

The AGA clinical practice guidelines for the use of probiotics with gastrointestinal disorders say:

‘The AGA makes no recommendations for the use of probiotics in children and adults with irritable bowel syndrome (IBS). While there are many studies examining this question, they are marked by significant heterogeneity in study design, outcome, and probiotics used.’

British Society of Gastroenterology

The BSG guidelines on the management of IBS recommend:

‘Probiotics, as a group, may be an effective treatment for global symptoms and abdominal pain in IBS, but it is not possible to recommend a specific species or strain. It is reasonable to advise patients wishing to try probiotics to take them for up to 12 weeks, and to discontinue them if there is no improvement in symptoms.’

Are probiotics safe for people with IBS?

Overall, research suggests that probiotics are safe for most people with IBS.

While reviews and meta-analyses reach slightly different conclusions about the effectiveness of individual probiotics, the available evidence generally suggests that adverse events are rare.

For instance, a review of 55 trials and more than 7,000 participants concluded that the risk of an adverse event from probiotics was no greater than with placebo.

However, some people with IBS who take probiotics may experience some relatively minor gut symptoms, including:

• abdominal cramping

• nausea

• soft stools

• flatulence

• taste disturbance

These side effects are uncommon. In some trials, gastrointestinal symptoms like these were more common among the placebo participants than those taking probiotics.

However, if you have a weakened immune system or any ongoing health issues, it’s important to speak with a doctor before trying probiotics.

What can we confidently say about probiotics and IBS?

Taken together, current evidence suggests that some specific probiotic strains may improve certain IBS symptoms for some people. This includes abdominal pain, bloating, bowel habits and overall symptoms. However, results are inconsistent across different strains, product types and outcomes.

Recent systematic reviews and meta-analyses tend to find benefits compared with placebo, but the certainty of the evidence is often low or very low, partly because studies vary in strains, doses, treatment duration and participants. 

It’s important to remember that evidence for one probiotic strain doesn’t necessarily apply to another, even if they’re strains from the same species. 

Because of these factors, clinical guidelines differ: Some allow or suggest trialling probiotics, while others recommend against them or make no solid recommendation. More research is needed to determine which strains work, for whom and for which IBS symptoms.

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