IBD and Lung Health: What a 2026 Systematic Review Found About the Connection

Inflammatory bowel disease is a condition of the gut, but its effects are not confined to the digestive tract. Crohn's disease and ulcerative colitis are recognised as systemic conditions that can affect joints, skin, eyes, and other organs. A category that has received growing clinical attention is the lungs and airways.

A 2026 systematic review and meta-analysis published in Frontiers in Immunology set out to examine, in a structured way, whether there is a meaningful bidirectional relationship between inflammatory bowel disease and obstructive lung diseases, conditions that narrow and inflame the airways. The results support the existence of an association, and the clinical conclusion is direct: if you have IBD, respiratory symptoms are worth taking seriously and reporting to your care team.

The Review

Published on 30 June 2026, the study by Ding C, Wang Y, Sun T, and Liu Z was a systematic review and meta-analysis conducted according to PRISMA guidelines and prospectively registered on PROSPERO (CRD420251169706) (Ding C et al., Frontiers in Immunology, 2026).

The researchers searched PubMed, Embase, and the Cochrane Library for observational studies (cohort studies, case-control studies, and cross-sectional studies) that reported on the association between obstructive lung diseases and IBD. A total of 30 studies were included. Obstructive lung diseases (OLD) were defined to include chronic obstructive pulmonary disease (COPD), asthma, and bronchiectasis. IBD was examined as both Crohn's disease and ulcerative colitis separately.

Because the studies used different measures of association (relative risks, hazard ratios, odds ratios), these were analysed separately in the meta-analyses to avoid mixing effect sizes that measure different things. Study quality was assessed using the Newcastle-Ottawa Scale.

COPD and IBD

For COPD, the review identified associations in both directions.

IBD was associated with an increased risk of developing COPD in the analyses. In the other direction, COPD was generally associated with increased risks of developing both Crohn's disease and ulcerative colitis. The review notes, however, that the analyses examining COPD leading to CD and COPD leading to UC showed substantial heterogeneity across included studies, meaning the results varied considerably between individual studies. The authors note this should prompt caution in interpretation.

COPD and IBD share biological mechanisms that may explain the link: both involve dysregulated immune responses, elevated systemic inflammation, and the accumulation of inflammatory cells in affected tissues. The shared immune and inflammatory landscape may contribute to a genuinely elevated mutual risk, though the observational nature of the studies means causation cannot be established.

Asthma and IBD: The Strongest Signal

The most consistent finding across the review was the bidirectional association between asthma and IBD.

IBD was associated with an increased risk of subsequent asthma in both the hazard-ratio-based analyses and the odds-ratio-based analyses. The relationship also held in the other direction: asthma was associated with subsequent IBD in the hazard-ratio-based analysis.

The authors describe the asthma-IBD association as "more consistent" than the COPD-IBD findings, and note that this pattern was generally stronger and more reproducible across the studies included. Asthma involves immune dysregulation at mucosal surfaces, the same type of surface affected in IBD, which may in part explain why this association is particularly consistent.

Bronchiectasis and IBD

For bronchiectasis (a condition in which the airways become permanently widened and are more prone to infection), available evidence suggested a positive association with IBD. However, the review's pooled estimate for IBD and subsequent bronchiectasis was imprecise, meaning the confidence intervals were wide and the strength of the association uncertain. The authors advise interpreting these findings with caution.

Bronchiectasis in the context of IBD is a known extraintestinal manifestation documented in clinical literature, particularly in Crohn's disease. The review adds quantitative evidence to this clinical observation, but acknowledges the data are not yet robust enough to draw firm conclusions.

Crohn's Disease More Strongly Linked Than Ulcerative Colitis

Across the different analyses, the bidirectional association between OLD and IBD was generally stronger and more consistent for Crohn's disease than for ulcerative colitis. This pattern is consistent with broader evidence suggesting that Crohn's disease tends to be more systemically inflammatory, affecting multiple segments of the gastrointestinal tract and having a higher propensity for extraintestinal manifestations.

What This Means in Practice

The review's clinical message is stated clearly by the authors: "Clinicians should be attentive to respiratory comorbidities in patients with IBD, and appropriate respiratory symptom assessment or screening may help early identification and management."

For patients, this translates to a practical point: respiratory symptoms in the context of IBD are not something to attribute automatically to other causes. A persistent cough, worsening breathlessness, or recurrent chest infections occurring alongside or after an IBD diagnosis are worth raising explicitly with a doctor.

What This Study Cannot Tell You

The 30 studies included in this review are observational. This means the findings describe associations (statistical relationships) and not cause-and-effect. An association between IBD and COPD does not mean that IBD directly causes COPD, or that everyone with IBD will develop lung disease.

The heterogeneity observed in some analyses (particularly the COPD-to-IBD direction) means results varied considerably between studies, which limits how precise the pooled estimates are. The authors used random-effects or fixed-effects models as appropriate to account for this, but substantial heterogeneity is a limitation the review itself acknowledges.

The finding is best understood as: having IBD is associated with a statistically elevated likelihood of also having or developing obstructive lung conditions, and the relationship appears to run in both directions. This warrants clinical attention; it does not warrant alarm.

Your clinician knows your individual situation best. If you have IBD and have noticed any changes in your breathing or respiratory health, ask them about it directly. If you have a lung condition and are experiencing gut symptoms, let your specialist know, as the full clinical picture matters.

AI-assisted curation; reviewed before publication. Always consult your doctor before making any changes to your healthcare.