Rajabi, Natalie, Ramdass, Prakash V A K · Frontiers in medicine · 2026 · DOI
A new systematic review combined data from 22 studies to examine how often irritable bowel syndrome (IBS) and ME/CFS occur together. Researchers reported that people with ME/CFS were substantially more likely to also have IBS compared to people without ME/CFS, and that about 37% of people with ME/CFS in these studies had IBS. However, the results varied considerably depending on which diagnostic criteria were used to define ME/CFS, suggesting uncertainty about the true overlap.
This systematic review demonstrates a strong statistical association between ME/CFS and IBS, supporting the clinical observation that gastrointestinal symptoms are common in ME/CFS populations. By analogy with the proposed shared mechanisms (immune dysregulation, autonomic imbalance, gut-brain signaling), the finding may help justify integrated diagnostic and management approaches. However, the magnitude of this association remains uncertain due to high heterogeneity and variation in case definitions.
This meta-analysis does not establish whether IBS causes ME/CFS, whether ME/CFS causes IBS, or whether either condition is mechanistically responsible for the other. It does not confirm the proposed underlying mechanisms (immune dysregulation, autonomic imbalance, or altered gut-brain signaling). The high heterogeneity (I² = 99.5%) and sensitivity to diagnostic criteria mean the reported 37% prevalence does not represent a stable, universally applicable estimate. Observational study designs cannot exclude confounding or differential ascertainment bias.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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Primary citation
Rajabi, Natalie & Ramdass, Prakash V A K (2026). Association between myalgic encephalomyelitis/chronic fatigue syndrome and irritable bowel syndrome: a systematic review and meta-analysis.. Frontiers in medicine. https://doi.org/10.3389/fmed.2026.1881784
BibTeX
@article{mecfsatlas-rajabi-2026-association-between,
author = {Rajabi, Natalie and Ramdass, Prakash V A K},
title = {Association between myalgic encephalomyelitis/chronic fatigue syndrome and irritable bowel syndrome: a systematic review and meta-analysis.},
journal = {Frontiers in medicine},
year = {2026},
doi = {10.3389/fmed.2026.1881784},
note = {PubMed: 42577233},
url = {https://www.mecfsatlas.com/evidence/rajabi-2026-association-between},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-08-12. https://www.mecfsatlas.com/evidence/rajabi-2026-association-between
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