The Truth About Symptoms Of SIBO Vs IBS; 5 Ironclad Facts

For those who suffer from gastrointestinal issues, understanding the symptoms of SIBO vs IBS can be a challenging but crucial aspect of managing their health. Misdiagnosing or mismanaging these conditions can lead to further complications and reduced quality of life.

In this article, we will dive into five ironclad facts about SIBO and IBS, explaining the differences, symptoms, and implications for those affected by these gastrointestinal disorders.

Small Intestinal Bacterial Overgrowth SIBO Explained

SIBO, or small intestinal bacterial overgrowth, is a condition characterised by an excessive number of bacteria in the small intestine.

A healthy small intestine has a relatively low amount of bacteria compared to the colon, but when the balance is disrupted, problems can arise. Bacterial overgrowth can lead to the fermentation of carbohydrates in the diet, causing gas, bloating, and other symptoms. [1]

Risk factors for developing SIBO include low stomach acid, poor gastrointestinal motility, and food poisoning, and may even arise form the use of certain medications. [2]

Additionally, individuals with autoimmune diseases like Crohn’s and celiac disease have a higher risk of developing SIBO. [2, 3]

Irritable Bowel Syndrome IBS Explained

IBS, or irritable bowel syndrome, is a functional gastrointestinal disorder that affects the large intestine. It is normally identified as a result of the symptoms which can include abdominal pain and changes in bowel movements, including constipation, diarrhea, or alternating between the two.

Symptoms Of SIBO vs IBS
Symptoms Of SIBO vs IBS

The exact cause of IBS is still not well understood, but it is believed to involve the gut-brain connection, with factors such as stress, diet, and hormonal changes playing a role in its development. [4]

Differences Between SIBO and IBS

While both SIBO and IBS cause gastrointestinal discomfort and share similar symptoms, there are crucial differences between the two conditions.

SIBO is primarily characterised by bacterial overgrowth in the small intestine, whereas IBS is a functional disorder that impacts the large intestine.

Symptoms of SIBO vs IBS

Although the symptoms of SIBO and IBS can be quite similar, there are some key differences. Both conditions share symptoms like abdominal pain, bloating, and gas, but the specific manifestation of these symptoms can differ between individuals.

SIBO Symptoms

Some common symptoms of SIBO include:

  • Abdominal pain
  • Bloating
  • Gas
  • Constipation, diarrhea, or both
  • Heartburn
  • Nausea
  • Carbohydrate intolerance
  • Malabsorption
  • Nutrient deficiencies
  • Stress and anxiety
  • Brain fog
  • Joint pain

IBS Symptoms

Common IBS symptoms include:

  • Abdominal pain and cramping
  • Bloating
  • Gas
  • Constipation or diarrhea
  • Mucus in stool
  • Food sensitivities or intolerances
  • Fatigue
  • Difficulty sleeping

In some cases, it has been found that up to 78% of IBS cases may be due to SIBO. This connection provides hope for IBS sufferers, as addressing the underlying SIBO could potentially resolve their IBS symptoms. [7]

5 Facts About Symptoms Of SIBO vs IBS

Fact 1: SIBO involves Bacterial Overgrowth in the Small Intestine

In SIBO, there is an overgrowth of bacteria in the small intestine, leading to an imbalance in the gut flora.

In contrast, IBS affects the large intestine and is characterised by symptoms such as cramping, bloating, and changes in bowel movements, but without bacterial overgrowth.

Fact 2: Different Root Causes

The root causes of SIBO include low stomach acid, poor gastrointestinal motility, food poisoning, and the use of certain medications.

IBS, on the other hand, has no specific identifiable cause and is considered a functional disorder, which means it is diagnosed when symptoms cannot be clinically explained by other conditions. [4, 8]

Fact 3: Connection to Autoimmune Diseases

Individuals with autoimmune diseases such as Crohn’s disease and celiac disease are at a higher risk for developing SIBO. [9]

People who suffer from other autoimmune conditions, including IBD and Celiac Disease are at higher risk of SIBO than others. The exact relationship between these conditions has not yet been established by Researchers, but they believe that both share some common pathophysiologic processes. They include:

  • Inflammation
  • Immune activation
  • Dysbiosis (microbiome alterations)
  • Gut permeability
  • Increased oxidative stress
  • Neurogenic injury, and
  • Defects of tight junction integrity.

However, more studies would have to be done on this subject to confirm any correlation. A specialist should always be consulted when experiencing worrying symptoms.

While IBS may coexist with autoimmune conditions, it is not directly linked to them as a risk factor.

Treating Leaky Gut Syndrome
Symptoms Of SIBO vs IBS – Different to Leaky Gut

Fact 4: Diagnosis Methods

As mentioned earlier, SIBO can be diagnosed using breath tests or small intestine aspirate and fluid culture tests. These tests are specifically aimed at detecting bacterial overgrowth in the small intestine. [1, 5]

IBS, on the other hand, is diagnosed by ruling out other gastrointestinal conditions and assessing the patient’s symptoms, as there is no specific test to diagnose IBS. [6]

Fact 5: Different types of SIBO

There are several types of SIBO, including:

  • Hydrogen dominant [10]
  • Methane dominant [11]
  • Mixed SIBO, and [12]
  • Hydrogen sulfide dominant. [13]

Small intestinal fungal overgrowth (SIFO) is also worth being aware of. [14]

These different types are characterised by the specific gases produced by the overgrown bacteria or the presence of fungi in the small intestine.

In contrast, IBS is not categorised into subtypes based on the type of gas or microorganisms involved but may be classified according to the predominant bowel habits, such as IBS with constipation, IBS with diarrhea, or mixed IBS.


What are the most Common Symptoms of SIBO?

When comparing the symptoms of SIBO vs IBS, it’s important to understand that there is some overlap between the two conditions.

However, the most common symptoms specific to small intestinal bacterial overgrowth (SIBO) include:
• Abdominal pain or discomfort
• Bloating and distension
• Indigestion
• Gas or flatulence
• Diarrhea
• Constipation
• Unintentional weight loss
• Fatigue

It’s essential to recognise the difference between SIBO and IBS, as the treatments for these conditions may differ. If you’re experiencing these symptoms, it’s important to consult a healthcare professional for proper diagnosis and treatment.

Additionally, you might also consider researching “SIBO vs IBS and Leaky Gut” to understand the possible connections between these gastrointestinal disorders and their impact on gut health.

What does SIBO look like in Stool?

In the context of symptoms of SIBO vs IBS, it’s essential to recognise that SIBO itself may not directly change the appearance of stool.

However, SIBO can lead to malabsorption and digestive issues, which can cause some changes in stool appearance. One such alteration is the SIBO stool color, which may become lighter, greasier, or even more foul-smelling than usual due to fat malabsorption or the presence of excess gas.

It’s important to note that these changes in stool can also be indicative of other gastrointestinal disorders, so consulting a healthcare professional for proper diagnosis and treatment is crucial if you experience persistent changes in your bowel habits.

What does a SIBO Flare Up feel like?

When discussing the symptoms of SIBO vs IBS, it’s important to know what a SIBO flare-up feels like, as this can help differentiate between the two conditions.

A SIBO flare-up is often characterized by worsening of typical SIBO symptoms, primarily affecting the small intestine. During a flare-up, individuals may experience increased abdominal pain, bloating, gas, nausea, and changes in bowel habits such as diarrhea or constipation.

These symptoms of SIBO vs IBS can be quite similar, so it’s essential to consult a healthcare professional for an accurate diagnosis and appropriate treatment plan.

Keep in mind that a SIBO flare-up can be triggered by various factors such as dietary changes, stress, or other underlying health conditions, making it even more crucial to work closely with a healthcare provider to manage symptoms effectively.

Where is SIBO Pain Located?

When considering the symptoms of SIBO vs IBS, it’s helpful to know where SIBO pain is typically located. SIBO, or small intestinal bacterial overgrowth, primarily affects the small intestine.

As a result, SIBO pain is commonly experienced in the abdominal region, particularly around the navel or lower abdomen. The pain can vary in intensity and duration, sometimes appearing as sharp or cramp-like sensations.

It’s essential to consult a healthcare professional if you’re experiencing persistent abdominal pain to determine the root cause, as the symptoms of SIBO vs IBS can be quite similar, and proper diagnosis is crucial for effective treatment.

What are the Strange Symptoms of SIBO?

When discussing the symptoms of SIBO vs IBS, some less common or strange symptoms of SIBO may arise. In addition to the typical symptoms of SIBO such as abdominal pain, bloating, gas, and changes in bowel habits, individuals may also experience some unusual symptoms.

These can include:
• Fatigue or weakness, often due to the body’s inability to absorb essential nutrients properly.
• Unintentional weight loss, which may occur as a result of malabsorption or difficulty digesting certain foods.
• Vitamin and mineral deficiencies, including anemia caused by iron or vitamin B12 deficiency.
• Skin issues such as rashes or eczema, potentially related to inflammation or an immune response triggered by the overgrowth of bacteria.

It’s worth noting that the symptoms of SIBO vs IBS can overlap, and it is not uncommon for SIBO symptoms to come and go or vary in intensity.

What is Gut Microbiome Dysbiosis?

Gut microbiome dysbiosis refers to an imbalance in the natural composition of microorganisms in the gastrointestinal tract. This imbalance can disrupt the normal functioning of the gut and potentially lead to various health issues. In the context of SIBO and IBS, gut microbiome dysbiosis plays a crucial role.

In SIBO the overgrowth is a specific form of gut microbiome dysbiosis that occurs in the small intestine. This overgrowth of bacteria interferes with the natural balance of microorganisms in the gut. It can cause malabsorption, inflammation, and various gastrointestinal symptoms.

SIBO is both a result and a cause of gut microbiome dysbiosis.

In IBS studies have suggested that gut microbiome dysbiosis might be one of the contributing factors. People with IBS often exhibit alterations in their gut microbiome composition compared to healthy individuals.

Dysbiosis in IBS may contribute to symptoms like bloating, abdominal pain, and changes in bowel habits. It is also suggested that certain IBS symptoms may predispose an individual to SIBO, creating an interconnected relationship between these two conditions.

Can SIBO symptoms come and go?

Yes, SIBO symptoms can come and go. The severity and frequency of symptoms may vary from person to person and may even fluctuate for an individual over time.

Factors such as diet, stress, and the presence of other gastrointestinal issues can influence the occurrence and intensity of SIBO symptoms.

If you are concerened about the symptoms of SIBO vs IBS, and experiencing difficulties, always seek medical support.


Understanding the differences between the symptoms of SIBO vs IBS is essential for the proper diagnosis and management of these conditions.

Although they share many similar symptoms, the causes and treatment approaches for SIBO and IBS differ significantly.

By recognising these distinctions and working closely with healthcare professionals, individuals affected by these gastrointestinal disorders can develop a tailored treatment plan that addresses their unique needs.

Armed with this knowledge of the truth about symptoms of SIBO vs IBS and the five ironclad facts shared in this article, patients and healthcare providers alike can work together to improve the quality of life for those living with these complex gastrointestinal conditions.

Through effective diagnosis, management, and support, individuals suffering from SIBO or IBS can regain control over their digestive health and reclaim the life they deserve.

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  1. “Small intestinal bacterial overgrowth (SIBO)” – Mayo Clinic Staff, 6 January 2022 [Mayo Clinic] [Archive]
  2. “Small Intestinal Bacterial Overgrowth” – A. C. Dukowicz, B. E. Lacy, G. M. Levine, February 2007 [PubMed] [Archive]
  3. “Gut Health and Autoimmune Disease — Research Suggests Digestive Abnormalities May Be the Underlying Cause” – A. Jacobs, February 2013 [Today’s Dietitian] [Archive]
  4. “Irritable bowel syndrome: Is it “irritable brain” or “irritable bowel”?” – S. K. Padhy, S. Sahoo, S. Mahajan, S. K. Sinha, October 2015 [PubMed] [Archive]
  5. “How to Recognize and Treat Small Intestinal Bacterial Overgrowth?” – B. Skrzydło-Radomańska, B. Cukrowska, 12 October 2022 [PubMed] [Archive]
  6. “Irritable bowel syndrome: Pathogenesis, diagnosis, treatment, and evidence-based medicine” – L. Saha, 14 June 2014 [PubMed] [Archive]
  7. “Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome: A Bridge between Functional Organic Dichotomy” – U. C. Ghoshal, R. Shukla, U. Ghoshal, Date [PubMed] [Archive]
  8. “Irritable Bowel Syndrome” – PennState Student Affairs Staff, Last Checked 21 April 2023 [PennState] [Archive]
  9. “Everything You Should Know About Small Intestinal Bacterial Overgrowth (SIBO)” – A. Balingit, C. Madormo, 3 April 2023 [Healthline] [Archive]
  10. “Hydrogen-producing small intestinal bacterial overgrowth is associated with hepatic encephalopathy and liver function” – K. Yokoyama, A. Sakamaki, K. Takahashi, T. Naruse, C. Sato, Y. Kawata, K. Tominaga, H. Abe, H. Sato, A. Tsuchiya, K. Kamimura, M. Takamura, J. Yokoyama, S. Terai, 25 February 2022 [PubMed] [Archive]
  11. “Methane SIBO and Constipation: 2023 Guide” – M. Cohen, 27 November 2022 [The IBS Gut Health Clinic] [Archive]
  12. “Association between Gut Dysbiosis and the Occurrence of SIBO, LIBO, SIFO and IMO” – M. Banaszak, I. Górna, D. Woźniak, J. Przysławski, S. Drzymała-Czyż, 27 January 2023 [MDPI] [Archive]
  13. “SIBO-HS: Hydrogen Sulfide (H2S)” – R. Brody, 1 May 2021 [Dr. Rober Brody] [Archive]
  14. “What Is SIFO and How Can It Affect Your Gut Health?” – C. T. Chavoustie, J. Seladi-Schulman, 4 December 2019 [Healthline] [Archive]

Last Updated on 2 months by D&C Editorial Team

About the Author

Christine has long been on the path to optimal health. With a history of weight loss coaching she is driven by a passion for nutrition, health and wellness. Having grown up in Africa before migrating to New Zealand, and then Australia, she has seen very strong contrasts in quality of life and is driven to help others understand the importance of taking a holistic approach to life.

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