IBS or SIBO: How to Tell One from the Other

If you have been experiencing digestive issues, you may have come across the terms IBS (Irritable Bowel Syndrome) and Small Intestinal Bacterial Overgrowth (SIBO). These two conditions share some common symptoms, which can lead to confusion and misdiagnosis.

How Often IBS is Mistaken for SIBO and Vice Versa

IBS is one of the most common gastrointestinal disorders, affecting up to 15% of the world's population. SIBO, on the other hand, is a relatively new condition that has gained attention in recent years. Studies have shown that up to 78% of patients with IBS may have SIBO, while up to 43% of patients with SIBO may have IBS. These numbers suggest that there is a significant overlap between the two conditions, making it challenging to distinguish one from the other based on symptoms alone.

Similarities in Symptoms

The symptoms of IBS and SIBO are similar, which can make it challenging to distinguish between the two. The similarity in symptoms is due to the fact that both conditions affect the gut microbiome, which is responsible for the digestion and absorption of nutrients. Both conditions can cause abdominal pain, bloating, gas, diarrhea, and constipation. Patients with either condition may also experience fatigue, brain fog, and anxiety, although these symptoms are less common.

Differences in Symptoms

Despite the overlap in symptoms, there are some differences between IBS and SIBO. IBS is a functional disorder that affects the large intestine, while SIBO is a bacterial overgrowth in the small intestine. For this reason, patients with SIBO may experience more severe symptoms after eating when the food leaves the stomach, while IBS symptoms may be triggered by stress or certain foods. Additionally, SIBO can cause nutrient deficiencies due to bacterial overgrowth, while IBS does not.

Can You Have Both IBS and SIBO?

It is possible to have both IBS and SIBO, as the two conditions share many of the same risk factors. These risk factors include antibiotics use, a diet high in sugar and processed foods, Stress is more common a a trigger for IBS, but may also contribute to the development of SIBO. If you have both conditions, treating SIBO may help alleviate some of your IBS symptoms.

Diagnostic Methods

To diagnose SIBO, your doctor may recommend a breath test. The test involves drinking a solution of lactulose or glucose and then measuring the levels of hydrogen and methane gas that you exhale. High levels of these gases may indicate the presence of bacterial overgrowth in the small intestine. To diagnose IBS, your doctor may perform a physical exam and run some blood tests. In some cases, they may also recommend a colonoscopy or stool test to rule out other conditions.


Your doctor can help you determine the best course of treatment based on your symptoms and medical history. In the meantime, you may find relief from your symptoms by following a low-FODMAP diet, reducing stress, and avoiding trigger foods like those high in sugar and processed foods.

Can IBS Turn into SIBO?

There is no evidence to suggest that IBS can turn into SIBO. However, patients with IBS may be more susceptible to developing SIBO due to their altered gut microbiome and digestion speed due to the adverse effects of IBS like gases or constipation.

Which Condition Is Worse?

SIBO can lead to more severe symptoms and nutrient deficiencies.

IBS or SIBO Checklist

Here is a checklist to help you differentiate between IBS and SIBO:

  • Do you experience abdominal pain, bloating, gas, diarrhea, or constipation? (Both IBS and SIBO can cause these symptoms.)
  • Do you experience more severe symptoms after eating? (This may indicate SIBO.)
  • Do you experience symptoms triggered by stress or certain foods? (This may indicate IBS.)
  • Have you been diagnosed with nutrient deficiencies? (This may indicate SIBO.)
  • Have you been diagnosed with a functional disorder? (This may indicate IBS.)

If you are experiencing digestive issues, seek medical attention to determine the underlying cause of your symptoms. By working with your doctor, you can develop a treatment plan to help alleviate your symptoms and improve your quality of life.

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