Medications’ Long-lasting Impact on Gut Microbiome

Recent research highlights the enduring changes in gut bacteria resulting from many commonly prescribed medications. The study involved over 2,500 participants from the Estonian Biobank, examining stool samples alongside their prescription histories. Researchers aimed to uncover links between medication use and variations in the gut microbiome — the community of bacteria and microorganisms in the digestive tract.

The findings revealed that most medications studied had associations with changes in the gut microbiome. Remarkably, these changes could be observed years after patients stopped using the medications. This extended impact was not confined to antibiotics. Antidepressants, beta-blockers, proton pump inhibitors (PPIs), and benzodiazepines also showed similar effects, each leaving a unique microbial “fingerprint” in the gut.

Dr. Oliver Aasmets, the lead author, commented: “Most microbiome studies focus on current medications, but our results demonstrate that past drug use is equally significant. It plays a surprisingly strong role in explaining individual microbiome differences.” This research could shape future microbiome studies, suggesting that the history of medication use should be considered when exploring connections between the microbiome and diseases.

Implications for Vulnerable Groups

Dr. Lucy Hooper, a general practitioner in London, noted that certain groups might be more susceptible to long-term microbiome changes. Developing infants and young children may be affected more profoundly as their microbiomes are still forming. Past research links early antibiotic use in children to conditions like asthma, obesity, and type 2 diabetes. Older adults, whose microbiome diversity naturally declines with age and who often require regular medication, may also face increased risks.

Benzodiazepines: A Notable Case

Benzodiazepines stood out in the research, exhibiting microbiome changes comparable to those caused by broad-spectrum antibiotics. However, not all drugs in this class produce identical effects. For instance, diazepam and alprazolam, both prescribed for similar conditions, differ in their impact on gut bacteria. This suggests that individual drugs, not just drug classes, should be individually assessed in microbiome research.

By analyzing follow-up stool samples from a subgroup, researchers observed shifts in gut microbes when participants began or ceased certain medications. These changes affirmed the role of the medications in altering the microbiome. Persistent effects were confirmed for PPIs, SSRIs, and some antibiotics such as combination penicillins and macrolides.

Factors Influencing Microbiome Recovery

Hooper highlighted that lifestyle factors might affect microbiome recovery following medication use. Diet, particularly fiber intake, influences microbial resilience. A fiber-deficient diet might hinder recovery after disruptions.

The Importance of Medication History

The study proposes that the gut microbiome reflects more than diet or current medications. It may retain traces of past medication use. Researchers argue that both scientists and clinicians should include medication history when interpreting microbiome data, as some changes thought to be disease-related could be medication-linked.

Hooper stressed that further research is necessary to uncover whether alterations in the microbiome due to medications cause health issues. While many studies show correlations, fewer demonstrate causation. Long-term tracking of microbiome changes in individuals is essential to understanding medication’s true impact. Despite concerns about microbiome effects, she advised against discontinuing prescribed medications without consulting healthcare professionals. “People should not stop medications due to microbiome worries, but it’s wise to regularly review prescribed medicines,” said Hooper.

Reference: Oliver Aasmets, et al., “A Hidden Confounder for Microbiome Studies: Medications Used Years Before Sample Collection,” mSystems, 2025.