Do GLP-1's like Ozempic or Mounjaro cause or worsen SIBO? Q&A with Dr Pimentel:

Quick answer: Yes, in 2025 studies were published showing an increased risk of SIBO with the use of GLP-1 medications, especially with 1 year or more of use. See Note, below.

This video delves into the growing use of GLP-1 medications, such as Ozempic, Mounjaro, Wegovy, and Zepbound, and their potential implications for gastrointestinal health, particularly concerning SIBO. It explores the balance between treating conditions like obesity and diabetes with potential unintended consequences.

Key Discussion Points:

• Rise of GLP-1: The significant increase in publication and awareness surrounding semaglutide and similar drugs in the past year.
• Mechanism of Action: These medications are known to slow stomach emptying and upper GI motility.
• Impact on SIBO Tests: The slowed stomach emptying can affect the results of SIBO tests, as substances may not leave the stomach as expected.
• Potential Link to SIBO:
  • While direct evidence is still developing at the time of recording ("early days"), the consensus is that anything slowing gut transit can logically lead to bacterial buildup (SIBO). 
  • The long-term effects of these medications on SIBO prevalence are not yet fully understood.
  • See Note below, for newer research.
• Implications for Existing SIBO:
  • For individuals already diagnosed with SIBO, some report that these medications can worsen symptoms like bloating due to further slowing of motility.
  • However, the reduced food intake associated with these drugs might lead to less fermentation, potentially balancing out the negative effects.
  • The overall impact on existing SIBO might be neutral for some, neither significantly worsening nor improving symptoms.
• Need for Further Research: Given the widespread and increasing use of these medications, studies are needed to understand their long-term gastrointestinal consequences.

Key Takeaways:

• Semaglutide and other GLP-1 drugs significantly impact gut motility, which has implications for small intestinal bacterial overgrowth.
• The effect of these medications on individuals with pre-existing SIBO is complex and can vary, with both potential for symptom worsening and mitigation due to reduced food intake.
• The rapid adoption of these drugs necessitates ongoing research into their full spectrum of effects. (See NOTE below)

NOTE:
Since the recording of this video, new studies showing a link between GLP-1 medicines and risk for SIBO have been published:

• Diagnostic Evaluation of an Increased Risk of Developing Small Intestinal Bacterial Overgrowth Associated with Glucagon-like Peptide-1 (GLP-1) Receptor Agonists and Dual GLP-1/GIP Receptor Agonists: A Global Retrospective Multicenter Cohort Analysis.  PMID: 40941750
  • Summary: this is the first large-scale study to identify an increased incidence of SIBO associated with GLP-1/GIP diabetes medications [Ozempic, Mounjaro]. The risk is associated with longer-term use (1 year). 

• GLP-1 Receptor Agonist Use Is Associated with Small Intestinal Bacterial Overgrowth and Intestinal Methanogen Overgrowth. DOI: https://doi.org/10.1177/26345161251353437
  • ​Summary: “GLP1 use is associated with SIBO, although diabetes may be a confounder.”

​​Products mentioned:
-GLP-1 medicines are Ozempic and Wegovy (Semaglutide)
-GLP-1 + GIP medicines are Mounjaro and Zepbound (Tirzepatide)