SIFO.
Fungal overgrowth in the small intestine. Often misdiagnosed as SIBO — different organisms, different protocol.
Same neighborhood. Different occupants.
SIFO is small intestinal fungal overgrowth — an abnormal proliferation of fungal organisms, primarily Candida species, within the small intestine, an environment that normally keeps fungal populations low. Research published in Digestive Diseases and Sciences identified SIFO in up to 25.3% of patients presenting with unexplained gastrointestinal symptoms, making it clinically significant but frequently missed.
Its symptoms overlap with SIBO so completely that many SIFO patients spend months on antibacterial protocols that never quite work. The differentiator is often the response to treatment: patients who fail standard SIBO protocols, or who feel worse on probiotic and carbohydrate-heavy approaches, frequently have a fungal component.
Fungal overgrowth typically develops when the balance of the gut microbiome is disrupted — most often by antibiotic use, a diet high in refined sugar, immunosuppression, or prolonged proton pump inhibitor use — allowing Candida to colonize parts of the GI tract where it's normally kept in check. Standard gastroenterology workups don't include fungal screening, so SIFO patients often cycle through years of symptom management without a correct diagnosis.
Our functional medicine team in Jacksonville and Orange Park uses organic acid testing, comprehensive stool analysis, and clinical history to identify SIFO, then builds a phased protocol to eliminate the overgrowth and rebuild the gut environment so it doesn't return.
Does this sound familiar?
Identify the organism.
What drives fungal overgrowth
SIFO doesn't happen randomly — it develops when the gut environment shifts in favor of fungal organisms. Understanding the triggers is the first step toward eliminating the overgrowth for good.
The common drivers: antibiotic overuse that disrupts microbial balance, high-sugar and high-refined-carbohydrate diets that feed yeast, immune dysfunction or suppression, chronic stress that weakens gut barrier integrity, prolonged proton pump inhibitor use, existing gut dysbiosis or SIBO, and hormonal imbalances that affect gut motility. Often several of these stack together.
Why SIFO gets missed for years
SIFO symptoms overlap heavily with IBS and SIBO, and standard gastroenterology testing simply doesn't screen for fungal organisms. The result is a diagnostic blind spot: patients are treated for what their symptoms resemble rather than for what's actually there.
This is exactly why specific testing matters. An organic acid urine test detects fungal metabolites, and stool PCR analysis can identify Candida and other species directly. Confirming the organism before treatment is what separates a targeted antifungal plan from another round of trial and error.
SIFO and SIBO can coexist
SIFO and SIBO are distinct conditions — one fungal, one bacterial — but they frequently occur together and produce overlapping symptoms, which is a major reason single-target protocols fall short.
When both are present, treating only the bacteria leaves the fungal overgrowth to keep driving symptoms, and vice versa. Comprehensive testing maps the full picture so the protocol can address every organism involved, in the right order, rather than clearing one and leaving the other to flare.
How treatment unfolds, phase by phase
SIFO treatment follows a deliberate sequence rather than a single intervention. It opens with a functional medicine evaluation — a comprehensive look at your health history, diet, lifestyle, and lab markers to identify the root drivers of the overgrowth and any coexisting conditions.
From there, advanced diagnostic testing (organic acids, comprehensive stool analysis, and DUTCH panels where hormones are involved) maps your gut ecosystem, and a targeted antifungal protocol paired with an anti-fungal nutrition plan starves the overgrowth while nourishing beneficial flora.
The final phase is restoration: rebuilding gut lining integrity and microbial diversity so the improvement lasts. Functional medicine evaluations include comprehensive lab work and a personalized plan, and our team walks you through every step from testing to protocol completion.
Questions, answered.
When SIBO protocols don't work.
Often the actual driver is fungal. A 30-minute consult to determine if testing is appropriate.
Book a SIFO consult