A new study published in Nature Medicine reveals that certain antibiotic treatments can alter the composition of the gut microbiome for years after use. Understanding the long-term effects of antibiotics on gut health is increasingly important as antibiotic resistance becomes a growing global concern.
The research, led by scientists at Uppsala University in Sweden, provides strong evidence about the duration and depth of these effects, highlighting the importance of considering the long-term impact of these medications on human health. The study analyzed data from nearly 15,000 adults.
Researchers found that antibiotic use can be associated with changes in the diversity and abundance of bacterial species in the gut, even four to eight years after treatment. “You can see that antibiotic use as far back as four to eight years ago is linked to the composition of a person’s gut microbiome today,” said Gabriel Baldanzi, the first author of the study. “Even a single course of treatment with certain types of antibiotics leaves traces.”
The gut microbiome plays a critical role in digestion, metabolism, and immunity. Sustained alterations to its composition may be linked to an increased risk of developing metabolic and chronic diseases, such as type 2 diabetes and cardiovascular disorders. Previous epidemiological studies have suggested links between frequent antibiotic use and these conditions, though the underlying mechanisms were not fully understood.
The study, conducted by an international team led by Uppsala University, analyzed the relationship between antibiotic use history and the current composition of the gut microbiome in 14,979 adults residing in Sweden. Researchers combined national prescription drug records with metagenomic analyses of fecal samples, allowing them to compare the microbiomes of individuals who had received different types of antibiotics with those who had not during the study period.
The research indicated that even a single course of certain antibiotics—such as clindamycin, fluoroquinolones, and flucloxacillin—could be associated with persistent alterations in gut bacterial diversity. These modifications were observed up to eight years after medication administration. In contrast, penicillin V, the most commonly prescribed antibiotic in Sweden for outpatient infections, showed smaller and shorter-lived changes in the microbiome.
Tove Fall, professor of molecular epidemiology and principal author, emphasized, “We believe that our results can guide future recommendations on antibiotic use, especially when choosing between two equally effective treatments, one of which has a lesser impact on the microbiome.”
The findings reinforce the importance of careful and tailored prescribing, not only for the immediate clinical picture but also for potential long-term side effects on the microbiome. The researchers suggest that the impact on the gut microbiome could be considered when making treatment decisions, particularly when equally effective alternatives are available.
This research comes as the threat of antimicrobial resistance (AMR) continues to grow, a concern for experts and international organizations like the World Health Organization (WHO). AMR occurs when bacteria, viruses, fungi, and parasites develop mechanisms to survive the action of drugs that were once effective. According to the WHO, it is currently linked to more than five million deaths each year and threatens to double that number by 2050 if urgent action is not taken.
Experts warn that overuse and inappropriate use of antibiotics in both human and veterinary medicine promote the emergence of resistant bacteria, often called “superbugs,” which can spread through the environment, water, and food. The Pan American Health Organization (PAHO) emphasizes that AMR compromises global food security and the effectiveness of medical treatments, affecting the health of people, animals, and ecosystems.
health authorities urge healthcare professionals, veterinarians, producers, and the public to implement good practices, early diagnosis, and responsible use of medications. Veterinarian Joaquín Basombrío, a specialist in antimicrobial resistance, emphasized in a statement to Infobae: “Antimicrobial resistance knows no borders or species. It affects people, animals, and the environment, so it can only be addressed from an integral vision.”
