Study: Many common drugs messing with our microbiomes

By Nikki Hancocks

- Last updated on GMT

Getty | cameravit
Getty | cameravit

Related tags microbiome Drug Medicine IBD Ibs

Many commonly used drugs significantly impair our microbiome health and increase our risk of intestinal infections, obesity and other serious conditions, according to a new study.

Researchers at the University Medical Center Groningen and the Maastricht University Medical Center found that 18 commonly used drug categories significantly impact the taxonomic structure and metabolic potential of the gut microbiome.

The study findings, presented at UEG (United European Gastroenterology) Week 2019, also suggest eight different categories of drugs also increase antibiotic resistance.

Lead researcher Arnau Vich Vila said it is already known that medication can impact the microbiome but this study helps to explain which drugs have what effect, as well as helping explain many side effects.

"We already know that the efficiency and the toxicity of certain drugs are influenced by the bacterial composition of the gastrointestinal tract and that the gut microbiota has been related to multiple health conditions; therefore, it is crucial to understand which are the consequences of medication use in the gut microbiome.

"Our work highlights the importance of considering the role of the gut microbiota when designing treatments and also points to new hypotheses that could explain certain side-effects associated with medication use."


The researchers looked at 41 commonly used drug categories and assessed 1883 faecal samples from a population-based cohort, patients with IBD and patients with IBS intermixed with healthy controls.

They compared the taxonomic and metabolic functions profiles of drug users to non-drug users, looking at the effect of single medication use and then combined medication use.

The changes observed could increase the risk of intestinal infections, obesity and other serious conditions and disorders linked to the gut microbiome.

The drug categories found to have the biggest impact on the microbiome included: Proton pump inhibitors (PPIs) used to treat peptic ulcer, H. Pylori eradication, Gastro reflux, Barrett's oesophagus as well as dyspepsia which affects between 11% and 24% of the European population; Metformin which is used as a treatment for Type 2 diabetes, affecting 10% of European adults; Antibiotics which are taken by 34% of the European population each year; and laxatives.

The gut microbiota of PPI users showed increased abundance of upper gastrointestinal tract bacteria and increased fatty acid production, while metformin users had higher levels of the potentially harmful bacteria Escherichia coli (E. coli).

The researchers also found that an additional seven drug categories were associated with significant changes in bacterial populations in the gut.

The use of certain antidepressants (called SSRIs) by those with IBS was associated with an abundance of the potentially harmful bacteria species Eubacterium ramulus.

The use of oral steroids was associated with high levels of methanogenic bacteria which has been associated with obesity and an increase in BMI.

United European Gastroenterology

UEG is a professional non-profit organisation combining all the leading European medical specialist and national societies focusing on digestive health.

UEG Week is the largest gastroenterology meeting in Europe and has developed into a global congress. It attracts over 14,000 participants each year, from more than 120 countries. 


Authors: Vich Vila, A. et al., 

"Impact of 41 commonly used drugs on the composition, metabolic function and resistome of the gut microbiome"​.

Presented at UEG Week Barcelona October 19-23, 2019.

Related topics Research Gut/digestive health

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