Antibiotics can save lives during serious infections, but new research suggests they may also have long-lasting effects on the gut microbiome. A study published in Nature Medicine found that some antibiotics may alter the balance of bacteria in the gut for as long as four to eight years after treatment.
Researchers analyzed prescription records and gut microbiome data from nearly 15,000 adults in Sweden. They discovered that people who had taken certain antibiotics years earlier still showed measurable differences in the diversity and composition of their gut bacteria compared with those who had not taken antibiotics during the same period. Even a single course of some antibiotics appeared to leave a detectable imprint on the microbiome.
The impact varied depending on the type of antibiotic used. Stronger associations were linked to drugs such as clindamycin and fluoroquinolones, while commonly used penicillin V appeared to cause smaller and shorter-lasting changes. Scientists say the findings highlight the importance of careful antibiotic use and may help guide decisions when doctors choose between treatments that are equally effective but may affect the gut microbiome differently.
SOURCE:
News Medical, March 11, 2026