Irritable Bowel Syndrome (IBS): Signs, Causes, and Treatments

Irritable bowel syndrome (IBS) is one of the most common digestive conditions in the world. Unpredictable bowel habits, chronic abdominal pain, and persistent bloating can make everyday life genuinely difficult, even without IBS causing permanent damage to the digestive tract.

Left unmanaged, IBS can impact your wellbeing beyond your gut health. It can drain your energy and take a toll on your mental health, with anxiety and depression occurring at higher rates in people with the condition than in the general population.

The good news is that IBS is treatable. This guide covers what IBS is, what causes it, how it differs from other gut conditions, and the most effective evidence-based strategies for getting your symptoms under control.

What Is Irritable Bowel Syndrome (IBS)?

Irritable bowel syndrome (IBS) is a common digestive condition that causes abdominal pain, bloating, and changes in bowel habits, like diarrhea or constipation. Unlike inflammatory bowel diseases, IBS doesn’t damage the digestive tract, but it can significantly disrupt daily life and overall well-being.

IBS is classified as a functional gastrointestinal disorder (FGID), meaning the digestive tract stops working properly despite no identifiable structural damage or disease 1 2. Rather than muscle spasms (the outdated “spastic colon” theory), IBS is now understood to be caused by disruptions in how the gut and brain communicate 3.

These gut-brain disruptions can cause food to move too slowly or too quickly through the digestive tract, or make the brain hypersensitive to normal amounts of gas or stool; altered serotonin levels likely play a role in this sensitivity 4 5. An unhealthy gut microbiome that drives inflammation may be an underlying trigger for these glitches in gut-brain communication 6.

IBS Symptoms: What Does IBS Feel Like?

The most common IBS symptoms are abdominal pain or cramping and changes in bowel habits, including diarrhea, constipation, or both (alternating) 7. Other symptoms of IBS include:

• Bloating and excess gas
• Feeling like a bowel movement is incomplete
• Mucus in the stool

Symptoms vary in type and severity from person to person and may come and go over time.

What Causes IBS? The Role of Gut Health

Several studies suggest that gut microbiome imbalances, particularly small intestinal bacterial overgrowth (SIBO), are very common in people with IBS and could contribute to IBS symptoms 8 9 10 11. For example, a meta-analysis that reviewed 50 clinical studies found that 8:

• More than one-third of IBS patients tested positive for SIBO.
• IBS patients were nearly five times more likely than healthy controls to test positive for SIBO. 

SIBO can increase inflammation, which may disrupt the gut-brain crosstalk, and can lead to the development of IBS 12.

One type of IBS, diarrhea-predominant IBS (IBS-D), is more significantly associated with SIBO than the other types 13. Around a third of people with IBS have IBS-D, a third have the constipation-predominant type (IBS-C), and a third have mixed symptoms (IBS-M). The gut microbiomes of people with IBS-D may be more likely to be imbalanced by SIBO 13.

Whether it comes from SIBO or not, poor microbiome health can result in a leaky gut, which may contribute to some IBS symptoms 14. A leaky gut allows food particles, bacteria, and toxins to escape into your bloodstream, causing inflammation and immune responses.

Not only that, but unhealthy or imbalanced gut microbes seem to stimulate IBS symptoms. These microbes simultaneously send signals to the central nervous system that can trigger mood changes. For example, a higher-than-average proportion of people with IBS develop depression and anxiety, highlighting the impact of the concept of a gut-brain relationship 15. 

Other Contributors to IBS

Food intolerances are also common IBS triggers. Often, certain carbohydrates, known as FODMAPS (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols), can cause symptoms for people with IBS 16.  

FODMAPS are poorly absorbed in the small intestine. As they move through the gut, they draw extra water into the small intestine through a process called osmosis. This can increase the amount of fluid in the bowel, contributing to bloating, cramping, and diarrhea in some people. When the FODMAPs reach the large intestine, gut bacteria ferment them, producing gas that can further worsen bloating, abdominal pain, and discomfort.

While this happens in everyone (even those without digestive sensitivities and imbalances), people with IBS are more likely to react with symptoms like abdominal pain or cramping. Excessive belching or flatulence and changes in bowel movements are also often experienced 17.

In some cases, IBS and food intolerances can result from the aftermath of a gastrointestinal infection 18. Post-infectious IBS has similar symptoms to other types of IBS, but it’s more likely to cause diarrhea.

IBS vs. Other Conditions: How to Tell the Difference

It’s worth knowing that a number of treatable gastrointestinal (GI) disorders can be misdiagnosed as IBS. 

A meta-analysis that looked at people diagnosed with IBS found that many cases actually had other conditions (known as comorbidity) 19. If the other GI issues were treated in these cases, it could make their IBS-like symptoms dissipate 19.

Within the analyzed studies, SIBO was one of the most common conditions confused with IBS 19. Although I talked above about how IBS and SIBO often occur together, they can also occur separately. In other words, SIBO can be a potential root cause of IBS, but it may also be a different condition altogether.

The second main condition confused with IBS in the study was carbohydrate malabsorption (different from FODMAP intolerance discussed above). In carbohydrate malabsorption, carbohydrates cannot be fully absorbed into the bloodstream, resulting in symptoms like bloating, gas, and diarrhea 20 21.

Other conditions that can be mistaken for IBS include:

• Bile acid diarrhea 
• Pancreatic exocrine insufficiency 
• Microscopic colitis 

Jumping too quickly to an IBS diagnosis can also make people overlook more serious gastrointestinal conditions. This can include celiac disease and inflammatory bowel diseases (IBD), such as Crohn’s disease and ulcerative colitis. For those with persistent IBS symptoms, it’s worth investigating whether celiac disease or IBD may instead be the cause.

That said, unless a client of mine has red flags of colon cancer—like severe anemia, blood in the stool, or unintentional weight loss—I recommend not rushing in with a barrage of invasive blood tests, stool tests, or colonoscopy procedures.

How to Treat IBS: An Overview of Natural and Conventional Options

Research has revealed a number of effective natural ways, including diet changes, probiotics, and stress reduction techniques, to deal with IBS symptoms. In my clinical experience, not all of these work for everybody, but one or a combination of them will usually bring some relief. 

Low-FODMAP Diet for IBS

FODMAPs are the carbohydrates mentioned above that can trigger digestive distress for those with IBS. 

A typical low-FODMAP diet begins with eliminating high-FODMAP foods, including:

• Apples, pears, mangoes, cherries, and dried fruit
• Artichoke, garlic, leek, onion 
• Mushrooms, cauliflower, and snow peas
• Bread and pasta (because of fructans, not gluten)
• Some legumes, such as kidney beans and split peas
• Soft cheeses, milk, and yogurt
• Cashews and pistachios
• Fructose and sweeteners containing sugar alcohols

After cutting out high-FODMAP foods for a while, most people notice a considerable improvement in IBS symptoms, like bloating and belly pain. However, it’s not sustainable to stay on such a limited diet for the long term. The most important phase in a low-FODMAP diet is therefore reintroducing higher-FODMAP foods one by one and noting gut reactions. 

Over time, food reintroduction reveals which carbohydrates are more tolerable than others and how to increase variety in the diet.

Monash University, in Melbourne, Australia, pioneered the low-FODMAP diet. They offer a very useful app to familiarize users with high-FODMAP foods and help them work out how much (or little) they can tolerate before having symptoms.

Most people become less sensitive to various foods over time as their gut health improves. However, it’s a good idea to keep some low-FODMAP foods around in the event of an unexpected IBS flare.

Probiotics for IBS

Many meta-analyses have shown that probiotics can effectively treat IBS with few side effects 22 23 24 25 26 27.

Collectively, these meta-analyses showed that probiotics can:

• Regulate bowel movements
• Improve bloating and abdominal pain
• Ease flatulence
• Improve energy levels and improve sleep

What’s great about probiotics is that they can help with symptoms at both ends of the spectrum of bowel movement frequency. For example, one study showed that Bacillus species probiotics reduced diarrhea and stool frequency in IBS patients 28. Other studies showed that probiotics can improve stool frequency and regularity in patients with constipation 29. These benefits can last a long time, as demonstrated in a study in which participants had less constipation for months, even after they stopped probiotic supplementation 25.

The probiotic strategy we recommend at the clinic is to take a few different high-quality strains. This approach is supported by two different meta-analyses that found that a multi-strain mixture, containing a blend of predominantly Lactobacillus and Bifidobacterium strains, improved IBS symptoms 22. It’s important to note that strain specificity is often key in IBS, as some probiotic strains may worsen symptoms for some people 30. At the clinic, the strains chosen and recommended are selected to avoid this outcome.

CLINICAL OBSERVATION: Although any well-formulated probiotic is likely better than none, I’ve had the most success with IBS patients when they’ve taken one from each of these three main probiotic categories:

• A Lactobacillus and Bifidobacteria blend (e.g., L. acidophilus, L. plantarum, B. infantis, and B. lactis).
• Saccharomyces boulardii (a beneficial yeast)
• Soil-based probiotics, usually Bacillus species

Some patients find that a Lactobacillus and Bifidobacterium blend is enough, but others report more benefit when they add in one or both of the Saccharomyces boulardii and soil-based categories, too.

For people who prefer this triple-therapy approach, my team formulated a convenient combination product that’s stable at room temperature and easy to travel with. 

A Gut Reset

For my clients who are having an IBS flare and struggling to tame their symptoms, I ask them to consider a gut reset by using an elemental diet shake that contains all necessary nutrients in a pre-digested form. Doing this, or simply fasting for 24–48 hours, can take the stress off the digestive system and reset the gut. 

There is some research suggesting that fasting can soothe an IBS flare, specifically in those who test positive for SIBO with a lactulose breath test 31. But for those who would rather not fast or have not tested positive for SIBO, another study showed that consuming a liquid elemental diet can do the same 32.

At the clinic, we’ve found that many do well with a “half” elemental diet, or replacing just one or two meals a day with an elemental shake. This is a great option for those who feel like replacing every meal with a shake is a bit too much. Another option is a 24-hour full reset, followed by a half elemental diet. Essentially, even though the elemental diet may seem restrictive initially, it’s actually a highly flexible and effective tool for those with stubborn gut issues.   

Stress Reduction 

Emotional stress and poor sleep are two of the most common IBS triggers. Managing both can make a meaningful difference in symptom frequency and severity.

Research supports several stress management techniques for IBS:

• Meditation
• Diaphragmatic breathing 33
• Cognitive behavioral therapy (CBT) 34 35
• Hypnotherapy 36 37

Exercise is another effective tool, particularly zone 2 cardio, which supports both stress resilience and gut motility. Yoga may offer additional benefits specifically for IBS, with studies suggesting it helps reduce symptom severity alongside its stress-relieving effects 38.

Sleep is often overlooked but is closely tied to gut health. Prioritizing good sleep hygiene by setting a consistent bedtime, keeping your room dark and quiet, and limiting screen time before bed can reduce the stress load on your digestive system over time.

For a deeper look at lifestyle strategies that support IBS relief, see our guide to IBS self-care.

Natural Supplements for IBS

Immunoglobulins are a newer type of supplement that supports the immune system by binding to, and neutralizing, unhealthy bacteria in the gut. Clinical trials have shown that immunoglobulins can improve IBS symptoms 39 40 41 42, even for IBS patients who don’t respond to other therapies 43.

A number of herbal remedies can also help with bloating and other digestive symptoms. In particular, peppermint oil supplements, peppermint tea, or the herbal supplement Atrantil can help to soothe digestive symptoms 44. With diarrheal IBS symptoms, a natural supplement containing creosote (such as Seirogan, a digestive herbal medication popular in Japan) can help ease symptoms at the moment 45.

For those with mainly constipation symptoms, natural laxatives are also worth investigating. For example, the soluble fiber psyllium can be effective for improving stool consistency. However, fiber can worsen symptoms for some, so it’s important to start slowly and drink plenty of water. Magnesium citrate is also a good option, especially for those who experience IBS-related constipation during travel.

IBS Medications: What Works and When to Use Them

Medication can be something to talk to your healthcare provider about for treating acute symptoms of an IBS attack. But keep in mind that most pharmaceutical IBS treatments simply provide symptom relief for digestive problems and do not address the root cause of IBS flare-ups.

That said, for IBS with diarrhea (IBS-D), Imodium (loperamide) is an over-the-counter medication that relaxes the smooth muscles of the digestive system and can improve stool consistency 46. Antidiarrheal medications specifically for IBS, including Viberzi (eluxadoline) and Lotronex (alosetron), are also available by prescription.

For IBS with constipation (IBS-C), over-the-counter osmotic laxatives, such as Glycolax or Miralax, can increase the water content of stool and help you pass bowel movements more often 47. As with any treatment you try, listen to your body to find out what works for your GI system.

Understanding IBS Is Key to Feeling Better

Once you know what triggers your IBS symptoms and have dealt with any potential underlying causes, you’re on your way to feeling better. The road to being symptom-free can have its ups and downs. But with the right gut health support, you’ll almost certainly have fewer symptoms over time.

If you incorporate the safe, natural treatments I outlined above, but your IBS symptoms don’t improve as much as you’d like, your situation may be more complex and need a more detailed approach. Book a private consultation with one of our clinicians. We’d love to help.

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