Do Acid Reducers Increase the Risk of IBD?

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

Acid reducers and gut bacteria

You have billions of bacteria living in your intestines. Some are helpful, and some are harmful. Some help you get energy from our food, and some influence the health of your immune system. Think of these bacteria as 1 big community in your gut.²

People with ulcerative colitis (UC) or Crohn's disease – 2 subtypes of IBD – may have acid reflux or heartburn and may take an acid reducer to help manage these symptoms. This type of medicine includes both proton pump inhibitors (PPIs) and histamine-2 receptor antagonists (H2RAs).^1,3

When you take an acid reducer over a long time, 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.^1,3

Acid reducers and ulcerative colitis relapse

A 2021 study found that taking PPIs or H2RAs in addition to UC medicine changed the course of remission for some people with UC. This study found that middle-aged people with UC and people with a short duration of the disease had a greater risk of relapse when acid reducers were added to their treatment regimen.⁴

Acid reducers and risk of hospitalization or surgery

Another study looked at the risk of hospitalization or surgery among people who took an acid reducer. 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.⁵

The reason researchers do matching studies like this is to make the results stronger. Matching rules out factors that might change what is being studied.⁵

This study reported links between both kinds of acid reducer and a higher risk of hospitalization or surgery. This result was found in people with both Crohn's disease and UC. But after the data was adjusted for certain factors, the results became more muddled. For example, there no longer appeared to be a link between H2RAs and hospitalization/surgery in people with UC.⁵

A lack of information

Clearly, more research is needed to learn more about the possible effects of taking acid reducers on people with IBD. Critics point out that both of these studies lacked information about:^3,5

• Why the study subjects originally needed an acid reducer
• Whether the study subjects smoked
• Whether the study subjects were also taking a narcotic pain reliever or nonsteroidal anti-inflammatory drug (NSAID)
• Accurate dates for when each subject's IBD started

PPI acid reducers may increase the risk of IBD

A newer study seems to have tilted the weight of evidence toward greater risks of IBD in people who use PPIs. This 2021 study combined data from 3 different observational studies. People included in the study had no prior history of IBD or cancer.¹

The study looked at health information from nearly 647,500 people. Some used an acid reducer, and some did not. 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 (BMI)
• Menopausal status
• Smoking history
• Alcohol use
• Physical activity
• Diet quality
• Incidence of gastroesophageal reflux disease (GERD)
• Ulcers or gastrointestinal bleeding
• Regular use of other drugs, including nonsteroidal anti-inflammatory drugs (NSAIDs), statins, and oral contraceptives or hormone therapy

They found that people taking PPIs had a 42 percent greater risk of developing IBD compared with people who did not use PPIs. The increased risk was slightly lower for those taking an H2RA – 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?

There are very real benefits of taking an acid reducer when you are living with IBD or 1 of its subtypes. But there may be some risks of doing so in the long term. Researchers are still working to understand the possible connections between the 2.

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.