Person holding their stomach. On their stomach is an image of a burst with an acid reducer pill in the middle that is surrounded by bacteria

Do Acid Reducers Increase the Risk of IBD?

You may have heard of a link between using a stomach acid reducer and flares with inflammatory bowel disease (IBD). Several different studies have looked into this question with mixed results. But a new study tips the weight of evidence toward a connection.1

Acid reducers and gut bacteria

People have billions of bacteria living in their intestines. Some are helpful, and some are harmful. Some help us get energy from our food, and some influence the health of our immune system. Think of these bacteria as 1 big community. And that community is in your gut.

People with IBD may need to take an acid reducer to manage their symptoms. This medicine includes both proton pump inhibitors (PPIs) and histamine-2 receptor antagonists (H2RAs).2

When you take an acid reducer long-term, studies show it can change the amount and types of bacteria in your gut. Some studies have found an increase in harmful bacteria and a decrease in helpful bacteria in people who take PPIs long-term. This sparks questions about whether taking acid reducers is linked to greater risks of IBD.3-5

Acid reducers and IBD hospitalization or surgery

In 2012, a study found that starting an H2RA nearly doubled the risk of people with Crohn’s disease needing hospitalization or surgery. The risk was much lower for people with ulcerative colitis (UC). The study found that people who used PPIs had no major change in their risk for hospitalization or surgery.6

In 2017, a different study showed that people who used an acid reducer had a slightly greater risk of hospitalization or surgery. This study also included people using both PPIs and H2RAs. But it matched these people with ones of a similar age and background who were not using an acid reducer. The reason researchers do matching studies like this is to make the results stronger. Matching rules out factors that might influence what is being studied.7

This second study reported a link between using an acid reducer (both kinds) and the risk of hospitalization or surgery. This result was found in people with both Crohn's disease and UC. But after doing statistical tests to adjust for a variety of factors that could influence the results, the link with acid reducers grew smaller. In people with UC, the link between H2RAs and hospitalization/surgery lost significance entirely.7

A lack of information

Critics point out that both of these studies lacked information on:3

  • Why an acid reducer was originally needed
  • Smoking status
  • If a narcotic pain reliever was also being used
  • Accurate dates for when someone’s IBD started

Both studies also lacked information about whether people had specific bacteria that can either trigger an IBD attack (Clostridium difficile) or protect against it (Helicobacter pylori).3

PPI acid reducers may increase the risk of IBD

A new study seems to have tilted the weight of evidence toward greater risks of IBD in people who use PPIs. This newer study pooled together data from 3 different observational studies. People included in the study had no prior history of IBD or cancer.1

The study included health information from nearly 647,500 people who both used and did not use an acid reducer. Most people were white and in their mid to late 50s. People who did not use PPIs tended to be a few years younger than those who did.1

The researchers controlled for the following factors that could influence results:1

  • Age
  • Race
  • Sex
  • Body mass index
  • Menopausal status
  • Smoking history
  • Alcohol use
  • Physical activity
  • Diet quality
  • Incidence of gastroesophageal reflux disease (GERD)
  • Ulcers or gastrointestinal bleeding
  • Regular use of nonsteroidal anti-inflammatory drugs (NSAIDs) or aspirin, statins, and oral contraceptives or hormone therapy

They found that people taking PPIs regularly had a 42 percent greater risk for IBD compared with people who did not use PPIs. The increased risk was slightly lower for those taking an H2RA, with 38 percent compared to people who did not. The results were similar for UC (36 percent greater risk) and Crohn's disease (62 percent greater risk) among people who took a PPI regularly compared to those who did not.1

What does this all mean?

First, there are very real benefits from taking an acid reducer when you are living with IBD or 1 of its subtypes. Second, there may be some risks in the long term, but researchers are still figuring it out.

If you have questions about acid reducers, talk to your doctor. Together, you can discuss the benefits and risks of taking acid reducers and whether they are right for you.

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