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Experts recommend that you talk to your doctor before beginning medications, and to not take antibiotics and other drugs unless it’s necessary. Getty Images
  • Researchers say common medications, including antibiotics and laxatives, can alter your gut microbiome.
  • They say these medications can also increase antimicrobial resistance mechanisms.
  • They add these medications can increase your risk of intestinal infections, gut disorders, and even obesity.

Indigestion, a bacterial infection, or constipation: Thanks to the marvels of modern medicine, there are widely available medications to combat all of these things.

But when you take these medications, you may be getting more than you bargained for.

According to a new study, some commonly used drugs — over-the-counter medications for heartburn and doctor-prescribed antibiotics among them — can extensively affect your gut microbiome.

Researchers at the University Medical Center Groningen and the Maastricht University Medical Center in The Netherlands also found that different categories of drugs increased antimicrobial resistance mechanisms.

They presented their findings at the United European Gastroenterology Week 2019 this week. The study hasn’t been published yet in a peer-reviewed journal.

Should any of this research give you pause? Given the attention gut health has received as of late, the answer is probably “yes.”

“In recent years we have learned that the gut microbiota is important in human health,” Arnau Vich Vila, a PhD student and professor of medical sciences at the University of Groningen and a lead researcher on the study, told Healthline. “Overall, our research suggests that the use of commonly used medication can have health consequences through modification of our gut microbial composition and function.”

Researchers looked at 41 commonly used drug categories. The ones they found to have the biggest impact on the gut microbiome included drugs used to treat indigestion called proton pump inhibitors (PPIs), antibiotics, laxatives, and metformin, the most commonly prescribed drug for diabetes treatment.

The researchers assessed 1,883 fecal samples from people with inflammatory bowel disease (IBD) as well as people with irritable bowel syndrome (IBS) and a control group of people without these conditions.

They said there was evidence some of the medications put people at increased risk of intestinal infections, obesity, and disorders linked to the gut microbiome.

The team’s findings regarding PPIs were the most alarming, in Vich Vila’s opinion.

“This is a group of medication which is sold over the counter with no need for prescription, rendering its use not controlled by physicians,” he said. “We have seen that the use of proton pump inhibitors has the largest impact on the gut microbiota composition, not only increasing certain potentially pathogenic bacteria in the gut but also increasing antibiotic resistance mechanisms.”

Vich Vila said their results have been validated by other research groups, “which also associated the use of these drugs to different conditions such as enteric [intestines-related] infections and cardiovascular events.”

Given what they’ve found, the researchers advise people to not take proton pump inhibitors without a recommendation from their doctors.

Your gut contains tens of trillions of microorganisms, including bacteria, fungi, and viruses, that are altered by different factors.

Medications are one factor. Diet and genetics are others.

“The gut microbiota plays an important role in our immune and metabolic functions, therefore alterations in its composition or structure can have an impact on these,” Vich Vila explained. “Our results suggest some interesting mechanisms that need further attention. For example, the use of oral steroids is related to the increased abundance of Methanobrevibacter smithii. This microbe has been related to obesity and increased body mass index [BMI], and an increase in weight is one of the common side effects of steroids use.”

Another example, Vich Vila said, is the use of PPIs.

“Epidemiological studies have identified that users have a higher risk of developing enteric infections. However, the mechanism by which this occurs is still not known,” he said. “Our findings suggest that changes in the gut microbiota induced by the use of this drug could facilitate these infections.”

Vich Vila noted there are other studies that report gut changes with obesity, diabetes, liver disease, cancer, and neurodegenerative diseases such as Alzheimer’s disease and multiple sclerosis.

“There is growing evidence of the role of microbiota in the neurological diseases, in what is called the ‘gut-brain axis,’” Vich Vila said. “To better understand which are the exact mechanisms that explain this relation, it is important to discriminate the causes and consequences of the microbial changes associated with these disorders.”

Their study, Vich Vila said, is an important first step to identifying potential relations between the use of medication and the gut microbiota.

He said more research is needed.

“We still need to understand how and why these changes occur,” he said. “For that, we need to combine in vitro experiments with longitudinal studies. Moreover, the study of the metabolism of these drugs will allow us to discriminate direct and indirect effects.”

Officials at the Food and Drug Administration (FDA) described the study results as “interesting.”

“It is encouraging to see studies on gut microbiota,” noted an FDA statement to Healthline. “We continue to gain a better understanding of the risk of intestinal infections, obesity, and other serious conditions and disorders linked to the gut microbiome. Gut microbiota plays an important role in a healthy digestive system.”

As a consumer of these drugs, what’s your next move?

Vich Vila said it’s still too early to draw conclusions about the health consequences of these changes to the microbiome.

But if you’re concerned about what you’re taking, talk with your doctor — and only take medications as needed.

“Drugs have been tested to be safe and are useful to treat multiple disorders,” Vich Vila said. “However, as we have seen in the past with the use of antibiotics, the unnecessary use of these drugs has become a problem. In the end, we advise patients to follow the recommendations of their doctor and to not take medication unnecessarily.”