An older man checks pills in a medication boxShare on Pinterest
Researchers say antibiotic use can increase the risk of inflammatory bowel diseases. BONNINSTUDIO/Stocksy
  • In a new study, researchers say the frequent use of antibiotics can increase the risk of inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis.
  • They note that the risk is the highest 1 to 2 years after antibiotic use that targets gut infections.
  • They add that the risk increases with each round of antibiotics while the risk wanes after antibiotic use is stopped.
  • Experts point out antibiotics are essential in certain incidents, but their use should take into account the inflammatory bowel disease risk.

Frequent use of antibiotics in people over the age of 40 could increase the risk of developing inflammatory bowel disease (IBD), according to a study published today in the online journal Gut.

Researchers used medical data from Danish citizens ages 10 and up who were not diagnosed with IBD at the start of the study period.

More than 6 million people were included. More than 5.5 million were prescribed antibiotics at least once during the study period, which lasted from 2000 to 2018.

There were 36,017 new diagnoses of ulcerative colitis and 16,881 of Chron’s disease, both of which fall under the IBD umbrella.

The researchers said they found that compared to people with no antibiotic use, people who took at least one round of antibiotics were more likely to develop IBD, regardless of age.

However, older age was associated with a higher risk.

The researchers also reported that:

  • People between 10 and 40 were 28% more likely to be diagnosed
  • Those between 40 and 60 were 46% more likely to receive an IBD diagnosis
  • People over 60 were 47% more likely to be diagnosed

As for Chron’s disease, the researcher reported:

  • People between 10 and 40 had a 40% higher risk
  • Those between 40 and 50 had the highest risk at 62% higher than those who didn’t take antibiotics
  • People over 50 had a 51% higher risk

The researchers also found that the risk factor for developing IBD was cumulative and subsequent antibiotic courses increased the risk by 11%, 15%, and 14%, respectively.

The increased risk rose even higher for people who took at least five rounds of antibiotics:

  • For ages 10 to 40, there was a 59% higher risk
  • For ages 40 to 60, the risk doubled
  • For people over 60, there was a 95% increased risk

The study noted that the highest risk of developing IBD occurs one to two years after antibiotic use. The risk decreases each subsequent year without antibiotic use.

  • For people 10 to 40, the risk was 40% higher for the first two years and then dropped to 13% four to five years later with no further antibiotic use
  • For people 40 to 60, the initial risk was 66% higher for the first two years and then dropped to 21% four to five years later with no further antibiotic use
  • For people over 60, initially, the risk was 63% higher and that dropped to 22% four to five years later when there was no further antibiotic use

The antibiotic nitrofurantoin was the only one not associated with IBD at any age.

“This antibiotic is more selective of urinary organisms than other broad-spectrum antibiotics,” explained Dr. Douglas Nguyen, a gastrointestinal physician at Providence Mission Hospital in Orange County, California.

The researchers noted that this study adds to the idea that the gut microbiome could have a crucial role in IBD and that many antibiotics have the potential to change the makeup of the gut microbiome.

They pointed out that they used prescriptions for antibiotics and they did not know whether a person took the medication and, if so, for how long.

“Often, antibiotics are a magical solution for many infectious diseases. However, they are also double-edged swords since they carry a lot of harmful effects in the short and long term,” said Dr. Sara Mesilhy, MRCP, a gastroenterologist at the Royal College of Physicians in the United Kingdom who is also on the medical team for

Despite the risk, there are times when antibiotics are necessary, experts say.

“We should not withhold or take away from this study that we should not be using antibiotics, but it’s essential to not just empirically prescribe in cases where antibiotics are not indicated,” said Dr. Adam Faye, an assistant professor in the Department of Medicine and the Department of Population Health at NYU Grossman School of Medicine in New York.

“I would emphasize that antibiotic stewardship is key- not just important to prevent drug resistance, but also has the potential to limit the development of IBD (particularly in older adults),” Faye told Healthline.

“I also think it’s important to remember that antibiotics can still alter the microbiome, including those not used to treat gastrointestinal infections,” he added.

Inflammatory bowel disease (IBD) covers two conditions – Crohn’s disease and ulcerative colitis. These conditions can cause chronic inflammation of the gastrointestinal tract, which can result in damage, according to the Centers for Disease Control and Prevention.

No matter which condition you have, typical symptoms include the following:

  • Diarrhea
  • Abdominal pain
  • Rectal bleeding or bloody stools
  • Weight loss
  • Fatigue

Medical experts do not fully understand what causes IBD, but possible causes include

  • An auto-immune reaction where the immune system responds to a perceived threat, such as a virus or environmental factors, and causes inflammation.
  • Someone in your family has IBD or another auto-immune disorder.

The current study indicates that exposure to antibiotics might also contribute to developing IBD.

“There are many environmental risk factors, including diets, NSAID exposure, and living in urbanized versus rural settings. Antibiotics and sanitation conditions could decrease biodiversity in the gut, leading to the risk for chronic inflammation,” Nguyen told Healthline.

Age could also play a role in the cause of IBD.

“In our practice, the positive family history of IBD patients was more pronounced in younger groups. In older patients, we tend to link it to environmental factors, such as antibiotic use,” Mesilhy told Healthline.