Gastroenterologist with 25 years of experience discusses what actually causes IBS, why most treatments fail, and the one approach she now recommends first

Dr. Andrea Chen is a board-certified gastroenterologist and professor of medicine at Northwestern University. She has spent 25 years treating patients with functional gastrointestinal disorders and has published over 80 peer-reviewed papers on gut-brain interaction.

In this article, she discusses the following three things:

• What the gut-brain axis is and how exactly this mechanism causes IBS symptoms
• Why the most common IBS treatments (diets, medications, probiotics) fail to produce lasting relief
• Which treatment has the strongest clinical evidence for resolving IBS long-term and why most patients have never been offered it

Read her full explanation below (plus, which treatment is her #1 recommendation for patients who have "tried everything").

1. What the gut-brain axis is and how it causes IBS

"The first thing I tell my patients is that IBS is not a food allergy."

Most patients who walk into my clinic have already cut out gluten, dairy, onions, garlic, and wheat. Many have done strict low-FODMAP elimination. Some have been living on five or six "safe" foods for months.

And they're still symptomatic.

Here's what I explain: IBS is classified by the Rome Foundation as a disorder of gut-brain interaction. Not a food intolerance. Not an allergy. A communication problem between your gut and your brain.

How this works:

• Your gut sends amplified distress signals upward to the brain
• Your brain sends amplified stress signals back down to the gut
• This creates a feedback loop where normal digestion gets interpreted as pain, urgency, or threat

This is called visceral hypersensitivity. It's present in the majority of my IBS patients, and it explains three things most people can't make sense of:

• Why you can eat the same meal two days in a row and react completely differently
• Why stress makes everything worse
• Why your symptoms flare unpredictably even when you're "doing everything right"

The food is not causing your IBS. Your nervous system's response to the food is.

2. Why diets, medications, and probiotics fail most IBS patients

"Every treatment I was trained to prescribe is a band-aid."

I say this as someone who has prescribed all of them. Here's the honest breakdown:

Low-FODMAP diet - Useful for identifying triggers short-term. But it doesn't change the underlying sensitivity. A study in Neurogastroenterology & Motility showed prolonged restriction can actually reduce beneficial gut bacteria. Most patients I see either can't sustain it or watch symptoms return when they reintroduce foods. I've had patients tell me they're "afraid to eat."

Antispasmodics (Buscopan, peppermint oil) - Can take the edge off a flare. But the Cochrane review found 4 out of 5 patients get no meaningful benefit beyond placebo. They do nothing for the gut-brain dysfunction driving the condition.

Probiotics - The treatment patients ask me about most. The evidence? A systematic review in Gastroenterology rated the certainty of evidence as "low to very low." Most commercial products have never been tested in IBS-specific trials. Patients spend hundreds of dollars cycling through brands.

Low-dose antidepressants (amitriptyline, SSRIs) - These actually target the right mechanism. The ATLANTIS trial showed real benefit for pain-dominant IBS. But effects are entirely medication-dependent: stop taking it, symptoms return. And side effects (drowsiness, weight gain, dry mouth) cause 38% of patients to discontinue.

The pattern: every one of these treats the gut end of a two-way problem. Remove the treatment, and the underlying dysfunction reasserts itself.

3. The treatment with the strongest evidence - and why most patients have never heard of it

"There is one treatment I now recommend first."

It's gut-directed hypnotherapy.

I understand the reaction. When I first encountered the research, I was skeptical too. But the data forced me to take it seriously.

Here's what the evidence shows:

The Manchester Protocol, developed over four decades of clinical research, was tested in a major trial with 354 IBS patients. In the hypnotherapy group, 70% achieved clinically meaningful improvement. At follow-up, those gains held. The control group regressed to baseline.

A systematic review found it had the largest effect size of any intervention studied for IBS. Larger than CBT. Comparable to the most effective drugs. With zero side effects.

Functional MRI research has shown it produces measurable neurological changes: reduced activation in brain regions that process visceral pain, increased activity in areas responsible for autonomic regulation.

Why it works when everything else fails:

It's the only treatment that retrains the gut-brain communication loop itself. It doesn't suppress symptoms. It teaches the nervous system to stop generating them. And because the change happens at the level of neural processing, the effects persist after treatment ends.

Why most patients don't know about it:

Fewer than 5% of IBS patients in the U.S. have ever been offered any form of gut-brain therapy. Most gastroenterologists were never trained in it. The American College of Gastroenterology now recommends it in clinical guidelines. The British Society of Gastroenterology gives it a Grade A recommendation. And it's now available through validated app-based programs at a fraction of the cost of in-person therapy.

Dr. Chen's #1 recommendation

If you've been living with IBS for years and you've cycled through diets, medications, and supplements without lasting results, the problem isn't that you haven't tried hard enough. The problem is that the treatments you were offered don't address what's actually driving your symptoms.

IBS is a gut-brain condition. The strongest evidence points to a gut-brain treatment.

If you haven't tried gut-directed hypnotherapy yet, you haven't actually tried everything.