SIBO vs. Candida: How to Know Which One Is Behind Your Bloating

If you’ve been dealing with relentless bloating and nothing seems to help, there’s a good chance something is growing where it shouldn’t be.

Two of the most common culprits I see in my practice are SIBO and Candida overgrowth. Both cause bloating. Both cause fatigue and brain fog. And both are widely missed in conventional medicine. But they are very different conditions. And treating the wrong one won’t get you better.

So let’s break down what each one actually is, how to tell them apart, and why getting the right answer matters so much.

What Is SIBO?

SIBO stands for Small Intestinal Bacterial Overgrowth. In a healthy gut, the small intestine has relatively few bacteria. Most of them live further down, in the large intestine. That’s where they belong.

In SIBO, bacteria end up in the small intestine in much larger numbers than they should. Once there, they ferment food before your body has a chance to absorb it properly. The result is gas, bloating, and over time, malabsorption of key nutrients like iron, B12, and fat-soluble vitamins.

SIBO is also closely linked to IBS. In fact, research suggests a significant portion of people diagnosed with IBS actually have SIBO at the root.

SIBO Symptoms to Know

  • Bloating that builds throughout the day, starting flat in the morning and worsening by evening
  • Excessive gas, often with a sulfuric or foul smell
  • Abdominal cramping and pain
  • Diarrhea, constipation, or both alternating
  • Nutrient deficiencies, especially iron and B12
  • Fatigue and brain fog without a clear cause

What Is Candida Overgrowth?

Candida is a type of yeast that naturally lives in your gut in small amounts. Normally, your good gut bacteria keep it in check. But when that bacterial balance shifts, Candida can grow out of control.

This is called small intestinal fungal overgrowth. Research shows it affects roughly 25% of people with unexplained gut symptoms. Even so, it’s still underdiagnosed in most clinical settings.

What causes it? Prolonged antibiotic use is the biggest trigger. Antibiotics wipe out good bacteria along with harmful ones. That opens the door for Candida to expand rapidly. Other common triggers include a high-sugar diet, chronic stress, hormonal changes like starting the birth control pill, and immunosuppressive medications.

Candida Overgrowth Symptoms to Know

  • Bloating that flares after eating sugar, refined carbs, or alcohol
  • Strong, unexplained sugar cravings
  • Recurring yeast infections or oral thrush
  • Skin issues like rashes, eczema, or fungal nail infections
  • Fatigue, brain fog, and mood changes
  • Sensitivity to fermented foods and wine

SIBO vs. Candida

How to Tell Them Apart

Here’s the honest truth: symptoms overlap a lot. Both conditions cause bloating. Both cause fatigue and brain fog. Both are driven by an imbalanced gut.

That said, there are patterns that point in one direction or the other.

With SIBO, bloating tends to build throughout the day. You wake up feeling fine and end the day looking visibly distended. It gets worse with high-fiber, fermentable foods like beans, garlic, onions, and wheat. These foods feed the bacteria in the small intestine and cause more fermentation.

With Candida, bloating is more directly tied to sugar and carbohydrates. A piece of fruit, a glass of wine, or anything sweet triggers it quickly. The sugar cravings are also a major tell. Candida actually feeds on sugar and drives your appetite toward it.

Background history matters too. SIBO is more likely if you have slow gut motility, low stomach acid, or a history of food poisoning. Candida is more likely if you’ve had repeated rounds of antibiotics, take hormonal birth control, or eat a diet high in refined carbohydrates.

And here’s something important: they can happen at the same time. In fact, treating SIBO with antibiotics without simultaneously supporting your good bacteria can trigger Candida overgrowth as a side effect. This is exactly why figuring out what you’re actually dealing with matters so much before you start any protocol.

How Are They Diagnosed?

This is the step most people skip. Guessing which one you have and self-treating without testing almost always leads to going in circles.

For SIBO, the standard test is a breath test. You drink a glucose or lactulose solution and breathe into a tube at set intervals. If bacteria are in your small intestine, they produce hydrogen or methane gas that shows up in your breath. It’s non-invasive, affordable, and widely available.

For Candida, testing is more complex. The most accurate method is a small intestinal aspirate with fungal culture. That’s invasive and not common in standard care. In functional medicine, I typically use a comprehensive stool test combined with organic acids testing. The organic acids test can reveal specific Candida metabolites in urine, giving us a clearer picture of what’s going on.

The Treatment Approach Is Very Different

This is why the diagnosis matters so much. What helps one condition can sometimes make the other worse.

For SIBO, a low-FODMAP diet reduces the fermentable foods that feed bacteria in the small intestine. It won’t cure SIBO on its own. But it reduces symptoms while antimicrobial herbs or targeted antibiotics work to reduce the overgrowth. Rifaximin is one of the most researched options for bacterial SIBO.

For Candida, the goal is to starve the yeast. That means cutting out sugar, refined carbohydrates, alcohol, and most fruit for a period of time. Antifungal support, whether herbal or pharmaceutical, is combined with rebuilding the good bacteria that keep Candida in check long-term.

Here’s the catch. High-fiber, prebiotic foods that are great for rebuilding gut bacteria can actually feed a bacterial overgrowth in SIBO. And a lower-carb, higher-protein diet that starves Candida can sometimes worsen hydrogen production in SIBO. There is real overlap and real tension between the two protocols. A one-size-fits-all gut plan won’t work here.

Stop Guessing. Start Testing.

If you’ve been bloated for months and nothing is working, there’s a reason. Treating the wrong condition, or treating both with a generic protocol, won’t move the needle.

Getting properly tested and then building a plan around what’s actually there is the only way to make real progress. This is exactly the work I do with my clients. We test, we find out what’s going on, and we build a targeted approach based on the results.

Ready to finally get answers? Book a free 15-minute discovery call with me. We’ll talk through your symptoms and figure out what testing makes sense for you.

And in the meantime, grab our free Gut Healing Meal Plan. It’s a great starting point for supporting a healthier gut environment while you work toward getting tested.

Research Cited

  • Small intestinal bacterial and fungal overgrowth: health implications and management perspectives. PMC (2025). PMC12030604
  • Diagnosis and treatment of small intestinal bacterial overgrowth: official position paper from the Brazilian Federation of Gastroenterology. PMC (2025). PMC12043196
  • Methane, bacteria, fungi, and fermentation: pathophysiology, diagnosis and treatment strategies for SIBO, IMO, and SIFO. PMC (2025). PMC12468957
  • Small intestinal fungal overgrowth: case report and literature review. PMC (2025). PMC12993699
  • Modulation of gut bacterial and fungal microbiota in fibromyalgia patients following a low-carb diet: evidence for Candida suppression and symptom improvement. PMC (2025). PMC12472566
  • A comprehensive review of probiotics, prebiotics, and postbiotics in the diagnosis and treatment of SIBO. PMC (2025). PMC11768010

Written by Jessica Mantell, M.S., LDN, Founder of NextGeneration Nutrition, Miami