It's not all in your head. It's not just stress. Your gut symptoms deserve a real workup.

Yes — for many patients, it works. The low FODMAP diet has the strongest evidence base of any dietary intervention for IBS, with multiple controlled trials showing 50–75% of IBS patients experience meaningful symptom improvement during the elimination phase. Evidence level: Strong for short-term symptom relief.

The critical part most patients aren't told: low FODMAP is a three-phase protocol — strict elimination for 2–6 weeks, structured reintroduction one FODMAP group at a time over weeks, then long-term personalisation. Staying in strict elimination indefinitely is associated with reduced gut microbial diversity, nutrient gaps, and disordered eating patterns. Working with a registered dietitian familiar with the protocol (Monash University trained the original researchers) makes a substantial difference. If low FODMAP doesn't help after 4–6 weeks of strict adherence, that's a useful piece of diagnostic information — your symptoms may be driven by something else (motility, visceral hypersensitivity, bile acid malabsorption, undiagnosed inflammatory disease) and the right next step is more workup, not stricter restriction.

Honest answer: breath testing is imperfect, and the SIBO testing world is somewhat contentious. Both lactulose and glucose hydrogen-methane breath tests have meaningful false positive and false negative rates. Glucose breath tests have higher specificity but miss SIBO in the distal small bowel. Lactulose tests have higher sensitivity but more false positives, especially in patients with rapid transit. North American Consensus criteria (2017) updated the interpretation thresholds, but many labs still use older cutoffs. Evidence level: Moderate, with active debate.

What this means practically: a positive breath test in a symptomatic patient is informative but not definitive. A negative breath test doesn't rule out SIBO if symptoms strongly suggest it. Methane-positive results (now called intestinal methanogen overgrowth, or IMO) are particularly associated with constipation and may respond differently to treatment. If you've had a borderline or unclear result, repeating it isn't always useful — sometimes a clinical trial of treatment is more informative than another test. A gastroenterologist who treats SIBO regularly will interpret the test in context rather than relying on the lab's cutoff alone.

Rifaximin (Xifaxan) has the strongest evidence for SIBO treatment, particularly hydrogen-positive SIBO and IBS-D. Multiple controlled trials show roughly 40–70% symptom response, with relapse rates of 30–50% within 6 months. For methane-positive cases (IMO), rifaximin alone is less effective and is typically combined with neomycin or metronidazole. Evidence level: Strong for rifaximin in IBS-D and hydrogen SIBO; Moderate for combination therapy in IMO.

Herbal protocols — typically combinations of berberine, oregano oil, allicin (garlic-derived), neem — have one notable comparative study (Chedid et al, 2014) suggesting comparable efficacy to rifaximin for SIBO. The study was small and not blinded, so the evidence is best described as Emerging. Herbals are generally cheaper but not always better tolerated; allicin in particular can be hard on the gut. The bigger issue with both approaches is recurrence — without addressing the underlying cause (slow motility, anatomical issues, low stomach acid, post-infectious changes), most patients relapse. Discussion of motility (prokinetics) and root causes matters as much as the antimicrobial choice.

A few reasons worth investigating. First, your symptoms may not be primarily food-driven — visceral hypersensitivity (the gut nerves over-reporting normal stimuli), motility disorders (gastroparesis, slow colonic transit, dyssynergic defecation), bile acid malabsorption, pelvic floor dysfunction, and undiagnosed conditions like microscopic colitis or endometriosis on the bowel can produce IBS-like symptoms that don't respond to dietary change.

Second, you may be eliminating the wrong things. Low FODMAP doesn't help everyone; some patients respond better to histamine reduction (especially with co-existing MCAS-type symptoms), gluten elimination beyond celiac (non-celiac gluten sensitivity is real but harder to study), or specific carbohydrate exclusions. Third, the gut-brain axis genuinely matters: stress, sleep, and trauma history measurably affect gut motility and pain processing. This isn't a way of saying it's psychological — it's saying the gut nervous system is real and reasonable to address. Gut-directed hypnotherapy and CBT for IBS have controlled-trial evidence comparable to dietary intervention for many patients. If diet has plateaued, broader workup (motility studies, calprotectin, celiac panel even if previously negative, sometimes endoscopy/colonoscopy) is the right next step.

A prokinetic is a medication that stimulates the migrating motor complex (MMC) — the cleansing waves that sweep the small bowel between meals. Impaired MMC activity is one of the most studied mechanisms behind SIBO recurrence, post-infectious IBS, and IBS-C. If you treat SIBO and it keeps coming back, or if your dominant symptom is constipation with bloating, prokinetics often matter.

Options vary: low-dose naltrexone (yes, the same drug used in fibromyalgia and ME/CFS — at 2.5–4.5 mg it has a prokinetic effect for some patients), low-dose erythromycin, prucalopride (Motegrity, the most evidence-based but expensive), tegaserod (limited availability), and ginger or Iberogast as gentler natural options with some evidence. Linaclotide (Linzess) and plecanatide (Trulance) work via different mechanisms and have strong evidence for IBS-C specifically. Evidence level: Strong for prucalopride and linaclotide in IBS-C; Moderate for low-dose erythromycin and LDN as adjuncts. A gastroenterologist who treats motility issues will know how to layer these — a gastro who only does endoscopy may not.

IBS is officially a clinical diagnosis, but "clinical diagnosis" doesn't mean "don't investigate." There are several scenarios where more workup is warranted: any blood in stool, unintentional weight loss, new symptoms after age 45–50, family history of colon cancer or inflammatory bowel disease, iron deficiency anemia, persistent night-time symptoms (waking from sleep with pain or diarrhea is uncommon in pure IBS), severe persistent constipation or alternating patterns that don't respond to standard care, and any failure to respond to first-line treatment.

Reasonable workup before settling on "IBS" includes: celiac panel (tTG-IgA with total IgA), fecal calprotectin (screens for inflammatory bowel disease — much more useful than CRP for the gut), TSH, basic CBC and metabolic panel, and depending on symptoms, breath testing, stool studies for infection, and imaging or endoscopy. Endometriosis on the bowel is commonly missed in women with cyclical IBS-like symptoms and warrants gynecologic evaluation. Pelvic floor dysfunction is missed often and requires anorectal manometry and referral to a pelvic floor PT. "Just IBS" without ruling these things out isn't a complete workup.