When Gut Disorders Show Up in the Mouth: What a New Systematic Review Reveals About IBS, Microscopic Colitis, and Oral Health

A Closer Look at a Hidden Connection

Irritable Bowel Syndrome (IBS) and Microscopic Colitis (MC) are well-known for causing chronic, non-infectious diarrhoea and abdominal discomfort. But what if these gut conditions also leave clues inside the mouth?

While Crohn’s disease, ulcerative colitis, and coeliac disease are already known to cause oral manifestations—sometimes even before intestinal symptoms appear—much less is known about how IBS and MC might affect the oral cavity. This new systematic review set out to answer that question.

Why Look at the Mouth?

The mouth is often described as the “mirror of systemic health.”

Inflammation, nutritional deficiencies, autoimmune activity, and microbial changes—common features of chronic gastrointestinal disorders—can all present as oral symptoms such as dry mouth, taste disturbances, halitosis, or even mucosal lesions.

Because IBS and MC share similarities with inflammatory bowel diseases (IBD)—including immune dysregulation, altered gut bacteria, and malabsorption—researchers hypothesized that these conditions might also have under-recognized oral manifestations.

Understanding these links matters. Earlier recognition of systemic symptoms in the mouth could:

• shorten diagnostic delays

• improve patient quality of life

• encourage better collaboration between dentists and physicians

What the Researchers Did

The authors conducted a systematic review following PRISMA guidelines.

They searched PubMed and Scopus and screened 710 unique articles, eventually identifying 17 studies that met strict inclusion criteria.

These studies examined:

• people with IBS who reported oral symptoms

• people with MC who showed oral or salivary gland involvement

• patients with oral autoimmune conditions (especially Sjögren’s syndrome) who were later diagnosed with IBS or MC

Across these studies, researchers evaluated symptoms such as dry mouth, halitosis, oral ulcers, burning mouth syndrome, and clinical diagnoses such as Sjögren’s syndrome (SS) or sicca complex.

What They Found

1. Strong Links Between IBS and Sjögren’s Syndrome (SS)

• Up to 62% of patients with Sjögren’s also had IBS.

• Conversely, 3–33% of people with IBS were diagnosed with Sjögren’s syndrome.

• Many IBS patients reported dry mouth, sometimes affecting half of the participants.

Because Sjögren’s is an autoimmune condition that directly affects the salivary glands, this suggests that a meaningful overlap exists between immune-mediated dryness and functional gut disorders.

2. Oral Symptoms Are Common in IBS

Across several studies, patients with IBS frequently reported:

• Dry mouth (xerostomia)

• Bad breath (halitosis)

• Foul or altered taste

• In isolated cases, burning mouth syndrome

Halitosis stood out as particularly common—up to 65% in some cohorts.

3. Microscopic Colitis Shows a Weaker but Notable Association

Compared to IBS, oral links in MC were less frequently studied, but the review found:

• 1–2% of patients with Sjögren’s also had MC

• 2–9% of patients with MC had Sjögren’s syndrome

• Dry mouth occurred in around 40% of MC patients in some reports

• One case described oral ulcers in collagenous colitis

While the association is less clear than in IBS, the pattern still suggests overlapping autoimmune or inflammatory pathways.

4. Not Enough Research on Other Oral Manifestations

Despite hints of additional oral complications—like ulcers, burning mouth syndrome, or taste disturbances—the evidence remains sparse. Many studies weren’t designed to examine oral findings in depth, so conclusions beyond SS, dry mouth, and halitosis remain limited.

Why These Findings Matter

This review highlights an important but under-recognized point:

oral symptoms may serve as early, accessible clues to systemic gastrointestinal disorders like IBS and MC.

For clinicians, this means:

• Dentists should be alert to unexplained dry mouth, recurrent ulcers, or burning sensations, especially in patients with abdominal complaints.

• Gastroenterologists should consider oral evaluations, particularly in patients with sicca symptoms or suspected Sjögren’s.

• Interdisciplinary collaboration may improve diagnosis and patient care.

For patients, better awareness means oral symptoms shouldn’t be dismissed—sometimes the mouth speaks before the gut does.

Conclusion

This systematic review provides growing evidence that IBS and MC are linked to oral health—particularly through dry mouth, halitosis, and comorbidity with Sjögren’s syndrome. While the connection is strongest for IBS, MC also shows meaningful associations.

Still, the authors emphasize a major gap: oral manifestations of these conditions are understudied. More research is needed to uncover how and why gut disorders influence the mouth—and how this knowledge can be used to improve early detection and patient outcomes.

Reference

Göthlin, H., Hasséus, B., Sjöberg, K., & Bankvall, M. (2025). Manifestations of the oral mucosa and salivary glands in irritable bowel syndrome and microscopic colitis – A systematic review. Acta Odontologica Scandinavica, 84, 349–362.

DOI: https://doi.org/10.2340/aos.v84.43870