You treated SIBO… but you’re still constipated


If you’ve been told you have SIBO (Small Intestinal Bacterial Overgrowth), you’ve probably gone through antibiotics, antimicrobials, or restrictive diets hoping it would finally give you lasting relief.


Maybe you felt better for a while… but then the bloating, backup, and discomfort came back.


You’re not imagining it and you’re not failing treatment.


The truth is: treating SIBO alone rarely fixes chronic constipation.


What the research actually says...


The connection between SIBO and constipation is real but complicated.


  • Methane-dominant SIBO (M-SIBO) is linked with slower motility. Methane gas can delay transit through both the small bowel and colon, which can worsen constipation.
  • But not all studies agree. Some show no meaningful difference in constipation between people with positive SIBO tests and those with normal results.
  • The relationship is often two-way: SIBO may worsen constipation for some, but constipation itself can also create the perfect conditions for bacterial overgrowth. 


So even when SIBO is present, it’s often a symptom of the system problem- not the root driver.


Why SIBO testing isn’t always the answer


Here’s where it gets messy: breath testing can be unreliable in constipated patients.


There are two main reasons:

  1. Slow motility changes the timing. In constipation, food and bacteria sit in the gut for longer. During a lactulose breath test, the sugar solution moves slowly, so gases from the colon (where bacteria normally live) show up earlier than expected. This looks like “SIBO” on paper, but it’s actually just normal colonic fermentation happening too soon.
  2. Stool can trap gases. Hard, retained stool can hold hydrogen and methane gases, releasing them in irregular bursts during the test. That release can create false peaks, again making the test appear positive when SIBO isn’t really present.


This is why lactulose breath tests often over-diagnose SIBO in constipation.


Glucose breath testing (GBT) is considered somewhat more accurate, but even then, results need cautious interpretation.


The bigger picture: it’s a system problem


Constipation is rarely about just bacteria. It’s about the system that controls how your gut moves and communicates.


That system includes:

  • Gut–brain communication → motility reflexes like the gastrocolic reflex often go “offline.”
  • Pelvic floor coordination → if muscles can’t relax properly, stool can’t pass even if motility is improved.
  • Gut microbiota balance → constipation itself alters the microbiome, feeding into a cycle of more bloating and discomfort.
  • Visceral hypersensitivity → the nerves in the gut become extra sensitive, amplifying symptoms.


If these system issues aren’t addressed, even the best SIBO treatment won’t last.


So… what actually works?


The path forward isn’t chasing the next antimicrobial or food restriction — it’s restoring rhythm to the system.


That’s exactly what I do with my patients:

  • For BC residents → I use my Gut Rhythm Method™, a personalized, 1:1 process that retrains motility, improves gut–brain communication, restores microbiota balance, and addresses pelvic floor issues when needed.
  • For those outside BC (or who want to start self-paced) → the Gut Rhythm Starter Plan™ takes you through the same 4-step system approach in a DIY format, with guides, trackers, and roadmaps that help you finally understand what your gut needs.


The takeaway


If treating SIBO hasn’t fixed your constipation, it’s not because you’ve failed- it’s because no one explained the bigger picture.


Constipation isn’t just about bacteria. It’s about the system. And once you rebuild that system, relief is no longer temporary.


👉 Click here to learn more about how to restore your gut rhythm.