Antibiotics & lifespan risk of IBD

Antibiotics & lifespan risk of IBD

March 21, 2023

Issue 06

Clinical Question

Is age linked to risk of IBD after antibiotic use?

Editor’s Bottom Line

These data support other observations of an increased IBD incidence after antibiotic exposure. However it remains unclear whether this association is truly causal.


Faye AS, Allin KH, Iversen AT, et al. Antibiotic use as a risk factor for inflammatory bowel disease across the ages: a population-based cohort study. Gut. 2023;72:663–70.


This analysis included data from 6,104,245 individuals aged 10 or older who were included in several national Danish registries between 2000 and 2018. Among other databases, information was retrieved from the Danish Prescription Register, which includes individual-level prescription data from community pharmacies, and from the Danish National Patient Register, which contains information on health care utilization and diagnostic codes.

The authors documented IBD diagnoses up to five years after antibiotic use, excluding the first year after antibiotic use to rule out pre-existing but undiagnosed IBD cases.

The analysis identified 52,898 patients diagnosed with IBD during the 18-year period and found that any exposure to antibiotics raised the risk of developing IBD. Those 40–60 years of age and those over 60 years of age had the highest risk of developing IBD after antibiotic use, with 48% and 47% higher odds compared to peers of the same age who had not used antibiotics (Incident Rate Ratio [IRR]: 1.48, 95% Confidence Interval [CI]: 1.43–1.54 for age 40–60; IRR: 1.47; 95% CI: 1.42–1.53 for 60 or older). Those 10–40 years of age had a lesser, but still significant, risk of developing IBD after antibiotic use, compared to their peers not exposed to antibiotics (IRR: 1.28; 95% CI: 1.25–1.32).

Each subsequent course of antibiotics further increased the risk of developing IBD by 11%, 15% and 14% for those aged 10–40, 40–60 and 60 or older, respectively. Individuals who received five or more courses of antibiotics were up to 2.12 times more likely than those who had not received any antibiotics to develop IBD (IRR: 1.69; 95% CI: 1.61–1.76 for 10–40 years of age; IRR: 2.12; 95% CI, 2.01–2.23 for 40–60 years of age; IRR: 1.95; 95% CI, 1.85–2.04 for 60 or older). 

The risk of developing IBD was greatest 1–2 years after antibiotic exposure. While it subsequently fell, the risk remained significant until 4–5 years after use.

Nitrofurantoin was the only antibiotic class not found to increase the risk of IBD, while nitroimidazoles and fluoroquinolones were associated with the highest risk of IBD development.

The risk of developing Crohn’s disease or ulcerative colitis was similar.


Study Design: Population-based registry analysis

Funding: The National Institute of Aging, the National Institute of Diabetes and Digestive and Kidney Diseases and the Danish National Research Foundation

Allocation: Not applicable

Setting: Multicenter

Level of Evidence: 2b