Why SIBO is underdiagnosed
Why SIBO is underdiagnosed
Medically reviewed by:
Dr John Freeman
Small Intestinal Bacterial Overgrowth (SIBO) remains one of the most under-diagnosed and misunderstood gastrointestinal conditions. Despite increasing research, many people continue to struggle for years without answers.
Here’s why.
1) IBS Diagnoses Are Much Easier to Make
Conditions like IBS, IBS-C, IBS-D, and IBS-M are broad, umbrella diagnoses.
Because they’re based on symptoms, not underlying mechanisms, they’re often used as a default label—long before anyone considers the possibility of SIBO.
2) Routine Gut Testing Often Appears “Normal”
Standard tools such as:
Colonoscopies
Endoscopies
Basic stool tests
…typically show no abnormalities in SIBO patients.
This leads many clinicians to assume “nothing is wrong,” when in reality, the issue is functional and microbial, not structural.
3) The Gut Has Been Historically Misunderstood
Much of what we know about the microbiome has been discovered in the past 20–25 years. This means:
Many practicing doctors were trained before SIBO was recognized as common.
Some still lack familiarity with diagnosis, breath testing, motility issues, or treatment protocols.
The overuse of the IBS label has often resulted in dismissed or minimized patient concerns.
4) Reliable, Evidence-Based Natural Treatments Are Hard to Find
The market is full of:
Gimmicky “gut healing” products
Generic probiotics that may worsen symptoms
Supplements not designed for SIBO
Finding science-backed antimicrobials is challenging. Some products can even exacerbate symptoms because they increase fermentation, feed bacteria, or ignore root causes such as impaired motility.
5) Access and Affordability Create Barriers to Treatment
A major challenge is that one of the best-studied SIBO antibiotics (rifaximin):
Is not approved for SIBO in many countries
Is frequently not covered by insurance
Can cost $500–$5,000 per course, depending on location
Often requires multiple rounds
High-quality herbal antimicrobials, however, are:
Far more affordable
Supported by research showing similar effectiveness to rifaximin
Better suited for addressing root causes such as dysbiosis and motility issues
A strong option for antibiotic non-responders or people preferring a natural approach
6) Many Medical Professionals Default to Generic Lifestyle Advice
Patients are often told to:
Reduce stress
Eat more fiber
Drink more water
“Try a probiotic”
While well-intentioned, these suggestions rarely address SIBO and often fail to relieve symptoms.
7) Treatment Often Focuses on Managing Symptoms—Not the Cause
Because the root cause isn’t identified, patients adapt by avoiding triggers:
Cutting out foods
Living with chronic bloating
Managing constipation or diarrhea
Limiting their lifestyles to avoid flares
This leads to years of unnecessary suffering while the underlying bacterial overgrowth remains unaddressed.
Expert Insights: Q and A with DR James Freeman (B.Sc. MB,BS Dean’s Roll of Excellence for outstanding academic achievement, founder of pioneering telemedicine company GP2U Telehealth in Australia. Also founder of a company that provides equitable access to medication)
Why is SIBO so under diagnosed?
It’s under recognised that it exists. One of the main drugs that’s used to treat SIBO isn’t approved for this specific use in many countries and doesn’t work to address underlying issues. It’s also often refused by insurance and costs anywhere from 500-5000 dollars for two weeks depending on where you live with many people requiring more than one course.
Herbal antimicrobials have been shown to be equally as effective with added benefits around microbiota composition and root cause issues like motility. The natural alternative can be a great option for people who want to take a natural approach and address underlying issues like dysbiosis or antibiotic non-responders/chronic relapses.
If there is no treatment due to access or lack of understanding about the best method, there is no ability to offer it to a patient.
Why do so many doctors give the diagnosis of IBS without getting to the root cause?
Doctors look for what they know how to look for. We have fecal MCS microscopy culture and sensitivities in terms of available commonly used tests. We have feces testing, but the thing is feces grow lots of things. Some we recognize as problematic like campylobacter and salmonella, but others that may be problematic, particularly when overpopulating the wrong area, we consider unproblematic, and we pay no attention to them. Some things also just do not grow.
We test for calprotectin, which indicates inflammatory bowel disease (Crohn’s disease and ulcerative colitis). Until the recent uprise breath testing, there is no widely used test that will diagnose SIBO. We would estimate less than 1% of GPs understand how to diagnose, test, and treat SIBO. We read the medical literature daily, and the topic only started emerging in recent years, and it hasn’t been greatly highlighted.
Why is breath testing not widely available?
Due to the lack of education around SIBO, it’s until recently that it started to become more common. Many governments do not fund breath testing, so patients will be out of pocket for all testing. The third type of SIBO was only recently discovered, so mass testing adoption for it is yet to occur.
Quote from a gastroenterologist at Johns Hopkins University: “SIBO was thought of as very rare before. In fellowship, the way we were trained was that this is something rare, like in those who’ve had surgeries causing a blind loop syndrome or have connective tissue disease such as scleroderma. We were just labeling patients [without classic risk factors] with IBS before, and they were not better because there was an underlying cause.”[1]
¹ Frost, n.d.
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