Antibiotic use, regardless of class, was associated with an increased risk for inflammatory bowel disease (IBD) among older adults, according to study results presented at Digestive Disease Week (DDW), held from May 21 to 24, 2022, in San Diego, California, and virtually.

The fastest growing subpopulation of IBD is among individuals aged 60 years and older. It is established that these patients have lower genetic risk, so it is likely that environmental exposures play an important role in the development of the disease later in life.

As antibiotic use has been associated with IBD onset among younger populations, researchers sought to evaluate whether antibiotic use plays a role in older-onset disease. Using nationwide registries in Denmark, researchers retrieved data on residents aged 60 years and older who were exposed to antibiotics between 2000 and 2018. Study participants were evaluated for IBD diagnoses.

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A total of 2,327,796 individuals aged 60 to 90 years were included in the cohort study. During the 22,670,484 person-year follow-up, 10,773 study participants were diagnosed with ulcerative colitis (UC) and 3825 with Crohn disease (CD).

Antibiotic use was associated with an increased risk for IBD (incidence rate ratio [IRR], 1.64; 95% CI, 1.58-1.71).

A positive dose-response relationship between antibiotic exposure and IBD risk was observed, in which patients who received 5 or more courses of antibiotics were associated with the greatest risk (IRR, 2.35; 95% CI, 2.24-2.47), followed by 4 (IRR, 1.96; 95% CI, 1.83-2.09), 3 (IRR, 1.66; 95% CI, 1.67-1.77), 2 (IRR, 1.54; 95% CI, 1.46-1.63), and 1 (IRR, 1.27; 95% CI, 1.21-1.33) course(s) of antibiotics.

Stratified by timeframe of exposure, risk for IBD was increased for more recent antibiotic use (1-2 years prior to IBD diagnosis; IRR, 1.87; 95% CI, 1.79-1.94) compared with more distant antibiotic use (2-5 years prior to IBD diagnosis; IRR, 1.42; 95% CI, 1.36-1.48).

Overall, risk for IBD was lowest for exposure to nitrofurantoin (IRR, 1.45) and highest for fluoroquinolone (IRR, 2.27). Stratified by IBD, risk for CD was higher for each drug class than it was for UC. CD risk was most highly associated with nitroimidazole (IRR, 2.62) and UC with fluoroquinolone (IRR, 2.21).

This study may have included some bias, as IBD is likely underdiagnosed among older adults.

The study authors concluded that antibiotic exposure, no matter what class, increased risk for IBD among individuals aged 60 years and older.

“Antibiotic stewardship is important; but avoiding antibiotics at all costs is not the right answer either,” Dr. Adam S. Faye, lead study author, said in a DDW 2022 news release. “If you’re not sure what you are treating, I would be cautious. If patients are coming in with clear infections, and they need antibiotics, they should not be withheld because of these findings.”


  1. Faye AS, Allin K, Iversen A, et al. Antibiotics as a Risk Factor for Older-Onset IBD: Population-Based Cohort Study. Presented at: DDW 2022; May 21-24, 2022; San Diego, CA. Abstract 400.
  2. Antibiotic use associated with inflammatory bowel disease in older adults: Crohn’s disease and ulcerative colitis higher in seniors with more rounds of antibiotic treatment. News release. DDW 2022. May 13, 2022.