Irritable Bowel Syndrome
Recurring tummy pain tied to bowel motions, with diarrhoea, constipation or both, plus bloating. Affects about 1 in 10 people. A real gut–brain glitch that doesn’t damage the bowel or cause cancer.
The IBS ladder
Start at the bottom, climb only if you need to. Your GP will usually check bloods (including for coeliac disease) first. Give each step 4 weeks before you judge it.
- Step 1 · Self-careRegular meals, movement and a diaryUnhurried meals, less alcohol, caffeine, fizz and sugar-free sweeteners (sorbitol, mannitol), regular exercise, and a 2-week food and symptom diary.
- Works
- Helps many with milder symptoms; exercise cut symptom scores by about 50 points (vs 5 with usual habits) in one trial
- Cost
- Free
- How long
- 2–4 weeks
- Watch for
- Don’t cut out gluten before a coeliac test: it can make the test falsely normal.
Eating lunch over the keyboard in four minutes is not a digestive strategy.
- Step 2 · PharmacySoluble fibre (psyllium)Start small and build up slowly. Helps both constipation and diarrhoea.
- Works
- Small benefit: about 1 in 5 fewer people with ongoing symptoms than on a dummy treatment (combined trials)
- Cost
- About $15–30 a tub
- How long
- 3–4 weeks to judge
- Watch for
- Bloating if you start too fast. Bran (insoluble fibre) often makes IBS worse.
Not all fibre is your friend. Psyllium, yes; bran, it’s complicated.
- Step 3 · PharmacyPeppermint oil capsules (enteric-coated)Relaxes gut muscle to ease cramps and bloating.
- Works
- More than doubles the chance of overall improvement vs a dummy treatment (12 trials combined); one of the better pharmacy options for pain
- Cost
- About $15–30 a month
- How long
- 2–4 weeks
- Watch for
- Heartburn and reflux.
Peppermint tea is lovely, but it’s not the same thing.
- Step 4 · PharmacyLoperamide for diarrhoea, or a macrogol laxative for constipationTargets your main bowel symptom.
- Works
- Good for the symptom they target in small trials; little effect on pain
- Cost
- About $10–30 a pack
- How long
- As needed, or daily for constipation
- Watch for
- Loperamide: constipation. Don’t use it with fever or blood in the stool.
Treat the bowel you have, not the one your friend has.
- Step 5 · PrescriptionLow-dose amitriptylineA small dose at night to calm gut nerves, not as an antidepressant.
- Works
- About 6 in 10 reported relief (vs 4.5 in 10 on a dummy treatment) in a large 2023 UK GP trial
- Cost
- Under the $25 PBS co-payment, about $10–20 a pack
- How long
- 3–4 weeks to judge; usually taken for at least 6 months
- Watch for
- Drowsiness, dry mouth, constipation. Dangerous in overdose, so store safely.
A tiny dose with a big job. Start low, go slow.
- Step 6 · Allied healthLow FODMAP diet, with a dietitianCut certain fermentable carbs for 2 to 6 weeks, then reintroduce them to find your personal triggers.
- Works
- About half to three-quarters improve; about a third fewer non-responders than on a usual diet (combined trials)
- Cost
- About $120–200 first visit; Medicare rebates with a GP care plan
- How long
- 2–6 weeks strict, then reintroduce
- Watch for
- Not a forever diet. If you’ve had an eating disorder or disordered eating, only do it with a dietitian, who may suggest a gentler approach.
The goal is finding your triggers, not living on rice and regret.
- Step 7 · Allied healthGut-directed hypnotherapy or CBTPsychological therapy that retrains gut–brain signals. In person, online or by app.
- Works
- In a Monash trial, about 7 in 10 improved, as many as with low FODMAP
- Cost
- Psychologist about $150–250 a session; app programs about $100–200
- How long
- About 6–12 weeks
- Watch for
- Takes regular practice. No swinging watches involved.
Not because it’s “all in your head”: because your gut and head are on a group chat.
Save your money
Popular, heavily marketed or often asked about, but the evidence is weak or says no.
- Food intolerance (IgG) blood testsNot valid for diagnosing food problems; they mostly diagnose your wallet.
- Colonic irrigation and colon cleansesNo evidence they help IBS, and they can cause dehydration, infection or, rarely, a tear in the bowel.
- Wheat bran and other insoluble fibreCan make bloating and pain worse. Soluble fibre (psyllium) is the one that helps.
- Faecal transplantTrials are mixed and guidelines don’t recommend it for IBS outside research. Definitely not a DIY project.
What you can do
- Eat regularly and slowly. Go easy on alcohol, caffeine, fizz and sugar-free sweeteners.
- Keep a 2-week food and symptom diary for appointments.
- Probiotics: try one for 4 weeks and stop if nothing changes.
See your GP if
- Symptoms began after age 50, or have recently changed
- Blood in your bowel motions, or black stools
- Weight loss you can’t explain, or diarrhoea waking you at night
- A family history of bowel cancer, coeliac disease or inflammatory bowel disease
Go to the emergency department for severe or constant tummy pain, vomiting, high fever, or heavy bleeding from the bottom.
Common questions
Does the low FODMAP diet work for IBS?
It helps about half to three-quarters of people. Cut out certain fermentable carbohydrates for 2 to 6 weeks with a dietitian, then reintroduce them to find your triggers. Don’t stay on the strict phase long-term.
Why is amitriptyline used for IBS?
A small dose at night calms gut nerves, not as an antidepressant. In a large 2023 UK GP trial, about 6 in 10 reported relief, vs about 4.5 in 10 on a dummy treatment. Allow 3 to 4 weeks.
Can IBS turn into bowel cancer?
No. IBS doesn’t damage the bowel or cause cancer. See your GP if symptoms start after 50, change, or come with blood, black stools or weight loss.
Do probiotics help IBS?
Some people benefit. Try one for 4 weeks and stop if there’s no change.
What causes IBS?
There’s no single cause. The gut and brain become more sensitive to normal gut movement and gas, and the bowel may move too fast or too slow. It often starts after a bout of gastro, stress or a change in gut bacteria, and it runs in families.
Is IBS serious?
IBS can really affect day-to-day life, but it doesn’t damage the bowel, cause cancer or shorten life. See a GP if you have bleeding, weight loss, symptoms waking you at night, or new bowel changes after age 50, as these need checking.
Does peppermint oil help IBS?
Yes, for many people. In trials, enteric-coated peppermint oil capsules eased pain and overall symptoms in clearly more people than a dummy capsule. Heartburn is the main side effect.
Helpful resources
- Monash FODMAP Diet appFrom the university behind the low FODMAP diet: traffic-light food guide, recipes and a symptom diary. About $13 one-off; best used with a dietitian. Also on Android.
- Monash FODMAP: Gut-directed hypnotherapy optionsExplains the choices: trained therapists or a 6-week app program. Free to read; therapy and app cost extra.
Evidence and more information
- Healthdirect: Irritable bowel syndrome
- Monash University: Hypnotherapy on par with low FODMAP diet
- University of Bristol: Amitriptyline helps IBS (ATLANTIS trial)
- NICE: Irritable bowel syndrome in adults
- BMJ (2008): Fibre, antispasmodics and peppermint oil for IBS
- BMC (2019): Peppermint oil for IBS, meta-analysis
- NIHR: Low-dose amitriptyline for IBS (ATLANTIS results)
- Gut (2022): Low FODMAP diet, network meta-analysis
- Am J Gastroenterol (2011): Exercise for IBS trial
maladywise.com/ibs/