IBS: causes, symptoms and treatment

Published August 2025 | 5 min read
Expert contributor: Distinguished Laureate Professor Nick Talley, neurogastroenterologist, University of Newcastle
Words by Trudie McConnochie

Knowledge about what causes IBS has improved significantly over the years. Here are the latest ways to identify and manage this digestive condition.

Most of us make decisions about food every day without too much difficulty, but for Melbourne mum Gemma, 34, every meal can be a minefield. Living with irritable bowel syndrome (IBS) means some foods cause uncomfortable and unpleasant symptoms, and since the condition can be unpredictable, it’s difficult to know how she might be affected from one day to the next.

“I can be fine for several weeks or days, and then I might accidentally eat one of my trigger foods – usually when we’re eating out or at someone else’s house – and then I’ll wake up the next morning with awful tummy problems, a really bad headache, bad lethargy and brain fog.”

Gemma began experiencing symptoms including bloating and pain when she was 17 and was diagnosed with IBS at 21. By the time she turned 30, her symptoms were taking a toll.

“I would go to work and struggle through the day, because I had this searing headache, I was really tired, and just had brain fog that made it impossible to work,” she says. “And then when I went freelance, I was at home, so it was a little bit easier. But it was getting to a point where it was really interfering with my productivity.”

After getting support from a naturopath who specialised in gut issues, and going through a lengthy process of food elimination, Gemma was able to zero in on the foods most likely to trigger her symptoms: legumes, excess fruit, chilli and starchy foods. But since the condition isn’t consistent, trying to stay on top of it can be stressful and frustrating.

What is IBS?

IBS is a digestive disorder that’s thought to affect about 30% of Australians. But according to Distinguished Laureate Professor Nick Talley, a world-leading neurogastroenterologist from the University of Newcastle, a 2022 NSW study he co-authored estimated IBS incidence at about 13.5%, when separated out from functional dyspepsia (persistent indigestion) and heartburn.

IBS symptoms can include:

• abdominal pain and cramping
• bloating
• mucus in stools
• wind
• incomplete emptying after a bowel movement
• constipation and/or diarrhoea with pain.

Prof Talley says that while IBS can have a debilitating effect on people, the condition can be very manageable for some.

“Some people have very mild symptoms and it doesn’t really disturb them, but unfortunately, there are quite a few people with IBS who have a very significant impairment of their quality of life.”

What causes IBS?

Experts’ understanding of IBS has grown enormously over the years, and they now know IBS isn’t just caused by poor gut function.

“It looks more likely that, in many cases, IBS is related to an infection that occurred or to a change in the gut bacteria,” explains Prof Talley. “This is probably because infections can lead to inflammation that damages the nerves and the functioning of the gut, and that change can persist for a long time, perhaps even for life.”

The biggest myth about IBS is that the symptoms you're feeling are all in your head, he says.

“It's more and more apparent, at least in my view, that IBS has an organic basis in many people. Physical or biological factors lead to the problem, and only later do emotional or psychological problems arise.”

Risk factors for IBS

Here are a few factors that can increase your likelihood of developing IBS.

• Family history: Research shows you’re two to three times more likely to develop IBS if you have a relative living with the condition, and genetics plays a role.
• Gut infections: Gastro illnesses can leave you with longer term inflammation in the gut, which can lead to IBS.
• COVID-19: While COVID-19 is a respiratory infection, it can cause gut issues and is linked to the development of IBS.
• Antibiotics: Excessive use can cause permanent changes in your gut microbiome, which can allow illnesses like IBS to take hold, says Prof Talley.
• Gender: Women are more likely to develop IBS. Prof Talley says experts don’t know exactly why, but it may be related to a more active immune response in women.

A 2024 Monash University study found a link between a history of heart problems and your likelihood of developing IBS, although more research is needed to fully understand this.

IBS diagnosis and treatment

Gemma was diagnosed by exclusion – meaning that her doctor diagnosed IBS when other digestive illnesses were ruled out. Tests including blood tests, stool tests, colonoscopy and flexible sigmoidoscopy (where a camera called an endoscope is used to look inside your colon) are done to rule out illnesses that can mimic IBS. These include coeliac disease, Crohn’s disease and bowel cancer, but Prof Talley says gastroenterologists now know the specific symptoms that strongly indicate IBS.

One of the challenges for people living with the condition is finding the right IBS treatments. This often involves trial and error – what works for one person may not work for another. That’s why Prof Talley recommends working with a dietitian for personalised guidance.

Lifestyle changes that can reduce IBS symptoms include:

• Increasing your fibre intake: This can be done by taking fibre supplements or eating more fibre-rich foods like fruits, vegetables and whole grains. Prof Talley notes that, for some people, fibre makes symptoms worse.
• Identifying FODMAP diet triggers: Fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) are typically found in foods like garlic, onions, apples, bread and chickpeas. With a dietitian’s support, you’ll remove these foods from your diet, then reintroduce them gradually to identify which trigger IBS symptoms. “It’s a complex process, but the diet does work in at least 50% of people,” says Prof Talley.
• Identifying other food triggers: IBS and diet go hand in hand. Prof Talley says certain foods like wheat, animal milk, soy and eggs can cause an allergy-like response in the gut that can trigger IBS symptoms.
• Reducing stress: Prof Talley says this can help calm gut disturbances by reducing the stress-hormone cortisol response.
• Trying other therapies: Cognitive behavioural therapy (CBT), yoga and hypnotherapy that targets the gut can be effective. For severe constipation, Prof Talley says pelvic floor physiotherapy can help. Eligible HCF members can access a range of evidence-based CBT programs through This Way Up^*, a digital mental health service designed to help you understand and deal with challenges like stress, insomnia, anxiety, depression and even chronic pain.  

Other people get relief from a hot water bottle, drinking peppermint tea, relaxation techniques like meditation and deep breathing, as well as medication for diarrhoea, constipation or gut spasms.

What to do if you think you have IBS

If you think you might have IBS, or you’re concerned about any digestive symptom, Prof Talley recommends asking your GP for a referral to a gastroenterologist. While a diagnosis of IBS might not be welcome, it’s possible to manage symptoms effectively to limit their impact on your life.

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