Antibiotics can leave lasting changes in the gut microbiome for up to eight years, according to a large-scale study from Sweden published in Nature Medicine.
The research, which analyzed data from nearly 15,000 individuals, found that even a single course of certain antibiotics can result in long-term alterations to intestinal bacteria. Scientists observed reduced microbial diversity and shifts in bacterial composition years after antibiotic use, including an increase in potentially harmful microbes like Escherichia coli and a decrease in beneficial genera such as Dialister, Veillonella and Eubacterium.
Researchers noted that the microbiome does not fully recover to its previous state, challenging the assumption that gut bacteria return to normal shortly after treatment ends. The study highlights that antibiotic use up to eight years prior was still linked to measurable differences in current gut microbiota.
Experts warn that repeated or prolonged antibiotic use is associated with increased risks of conditions such as obesity, type 2 diabetes, cardiovascular disease, and colorectal cancer. The findings underscore concerns about the long-term health consequences of antibiotic exposure, even when used appropriately to treat infections.
The study’s lead researcher, Gabriel Baldanzi of Uppsala University, emphasized that “even a single treatment with certain types of antibiotics leaves lasting traces” in the digestive system.
These results suggest that the impact of antibiotics on gut health extends far beyond the immediate aftermath of use, with implications for both individual health and public health strategies around antibiotic stewardship.
