Homearrow Blogsarrow Small Intestinal Fungal Overgrowth (SIFO) | Symptoms, Testing, Treatment
May 27, 2025

Small Intestinal Fungal Overgrowth (SIFO) | Symptoms, Testing, Treatment

SIFO is a hidden cause of chronic bloating, brain fog, fatigue, and food sensitivities. Learn how we diagnose fungal overgrowth with the Organic Acids Test (OAT), stool analysis, and symptom review—and treat it with antifungals, gut repair, and immune support at Revolution Health.

Small Intestinal Fungal Overgrowth (SIFO) | Symptoms, Testing, Treatment

Understanding SIFO: Small Intestinal Fungal Overgrowth and How to Treat It Effectively

What is SIFO?

SIFO, or Small Intestinal Fungal Overgrowth, is a lesser-known but increasingly recognized condition in which fungal organisms—primarily Candida species—colonize the small intestine in excessive amounts. Like SIBO (Small Intestinal Bacterial Overgrowth), SIFO interferes with digestion, disrupts immune regulation, and produces significant inflammation.

Although often overlooked, SIFO may be present in 25–40% of patients with chronic, unexplained GI symptoms, and it frequently occurs alongside or after bacterial imbalances—especially if treatment includes antibiotics.

Common Symptoms of SIFO:

  • Persistent bloating or distention

  • Gas, belching, or early satiety

  • Fatigue or brain fog, especially after eating

  • Constipation, diarrhea, or mixed bowel habits

  • Skin rashes or itching (often in warm, moist areas)

  • Sugar and carb cravings

  • Exacerbation of symptoms after eating sugar, wine, cheese, or vinegar

  • Recurrent yeast infections or oral thrush

What Causes SIFO?

Fungal organisms like Candida albicans normally exist in low amounts in the GI tract. However, when microbial balance is disrupted, or immune defenses are compromised, fungi can proliferate in the small intestine, leading to gas, toxins, and inflammation.

Common Risk Factors:

  • Frequent or recent antibiotic use

  • Use of proton pump inhibitors (PPIs)

  • Corticosteroids or immunosuppressants

  • High-sugar or high-refined carbohydrate diets

  • Diabetes or impaired glucose tolerance

  • Weakened immune system (autoimmune disease, chronic stress)

  • Recurrent vaginal yeast infections, athlete’s foot, or sinus fungus

Fungal overgrowth often occurs after failed or incomplete SIBO treatment and is commonly missed when only bacterial imbalances are investigated.

How Do We Test for SIFO?

SIFO is trickier to diagnose than SIBO because traditional breath tests only measure bacterial gas. However, there are now several functional medicine tools that can reliably identify fungal overgrowth in the gut.

1. Clinical Evaluation & Symptom History

  • Sugar cravings or worsening symptoms after sweets

  • Recurrent yeast or fungal skin infections

  • GI symptoms that persist despite SIBO treatment

An experienced provider can often suspect SIFO based on clinical patterns, particularly when symptoms worsen with sugars or persist post-antibiotics.

2. Stool Testing (GI-MAP, Gut Zoomer, etc.)

  • Detects Candida species or other fungi via DNA (PCR) technology

  • Also evaluates the immune response via secretory IgA or anti-Candida markers

  • Can identify dysbiosis, inflammation, and enzyme imbalances as well

3. Therapeutic Trial of Antifungals

  • In some cases, a carefully administered antifungal protocol can be both diagnostic and therapeutic

  • Significant symptom improvement after antifungal therapy often confirms SIFO

4. Organic Acids Test (OAT)

The Organic Acids Test is a urine-based metabolic test that evaluates dozens of metabolic pathways, including fungal overgrowth markers. It’s a particularly useful option when:

  • Stool testing is inconclusive

  • There's suspicion of systemic Candida or non-GI symptoms

  • There’s a need to assess broader metabolic dysfunction, mitochondrial health, or oxalate overload

Key OAT Markers for Fungal Overgrowth:

  • Arabinose: One of the most specific markers of Candida overgrowth

  • Tartaric acid, citramalic acid, and others: Suggest fungal metabolism and dysregulation

  • Oxalates: Often elevated in chronic fungal or mold cases

The OAT is an excellent tool when SIFO is suspected in patients with neurological symptoms, fatigue, or systemic inflammation beyond the gut.

Why SIFO Frequently Recurs

Fungal overgrowth is stubborn and resilient. Candida and other fungi can:

  • Form biofilms (protective coatings that shield them from immune and drug attack)

  • Mutate rapidly, becoming resistant to common antifungals

  • Hibernate in tissues and return after short-term suppression

Because of this, relapse is common unless root causes—like motility issues, immune imbalance, and diet—are addressed. It’s also essential to treat fungal overgrowth longer than bacterial overgrowth, often requiring 4–8 weeks or more.

How We Treat SIFO at Revolution Health

Our SIFO protocol is rooted in an integrative, root-cause approach that prioritizes healing the gut, restoring immune balance, and preventing recurrence.

1. Antifungal Therapy (Targeted Eradication)

Depending on your test results, history, and preference, we may use:

Pharmaceutical Antifungals:

  • Nystatin (non-systemic) or Fluconazole, Itraconazole (systemic)

  • Longer courses often needed than typical antibiotic treatment

Botanical Antifungals:

  • Berberine, caprylic acid, garlic (allicin), oregano oil

  • Pau d’arco, black walnut, cinnamon bark extract

We often alternate or combine botanicals and pharmaceuticals for synergistic effect.

2. Biofilm Disruption

Candida hides in biofilms that reduce treatment effectiveness. We use:

  • Enzymes: InterFase Plus, nattokinase, or serrapeptase

  • Chelating agents: EDTA in appropriate cases

3. Antifungal Diet

We guide patients through a carefully structured anti-Candida diet:

  • Eliminate sugar, refined carbs, alcohol, fermented foods, yeast, and mold-containing foods

  • Emphasize protein, non-starchy vegetables, and healthy fats

  • Gradual reintroduction of certain foods once symptoms stabilize

4. Gut Repair & Immune Resilience

After fungal load is reduced, we promote gut healing with:

  • L-glutamine, zinc carnosine, quercetin, and collagen

  • Peptides like:

    • BPC-157 – supports mucosal repair and gut lining

    • KPV – potent anti-inflammatory for the gut lining and immune regulation

5. Motility & Microbiome Reset

  • Support the migrating motor complex (MMC) with natural or pharmaceutical prokinetics

  • Gradual reintroduction of probiotics—starting with:

    • Saccharomyces boulardii (a beneficial yeast that competes with Candida)

    • Spore-forming probiotics that don’t exacerbate symptoms

Summary

SIFO is a common but underdiagnosed contributor to chronic GI and systemic symptoms. It frequently coexists with or follows SIBO and is often the missing piece in patients who don’t respond to typical protocols.

Using tools like stool analysis, Organic Acids Testing, and thorough clinical evaluation, we identify SIFO accurately and treat it comprehensively—with a blend of antifungals, biofilm disruptors, gut repair agents, and immune modulation.

If you’re experiencing persistent bloating, fatigue, food sensitivities, or chronic gut dysfunction—even after SIBO treatment—SIFO could be the cause.

Start Your Recovery at Revolution Health & Wellness

Our Tulsa-based team specializes in complex gut health cases and uses advanced functional testing, like the Organic Acids Test and stool analysis, to identify and resolve fungal overgrowth. We don’t just treat symptoms—we heal the root cause.

🩺 Schedule your consultation at RevolutionHealth.org and take the first step toward full-body healing.