Some\u00a0everyday medicines \u2013 not just antibiotics \u2013 could\u00a0influence\u00a0gut bacteria in ways that affect how other treatments work, according to a new review by the Medicines and Healthcare products Regulatory Agency (MHRA)\u00a0and University of Glasgow.\u00a0The findings\u00a0open up\u00a0opportunities to better tailor treatments to individuals and improve how medicines are used together in real life.\u00a0<\/p>\n
The review, published today (23\u00a0December) in\u00a0Nature npj Antimicrobials and Resistance<\/a>\u00a0by\u00a0Shirley\u00a0Do Nascimento and\u00a0colleagues,\u00a0brings together\u00a0evidence that a wide range of drugs \u2013 including diabetes treatments and antipsychotics \u2013 can change the make-up of\u00a0the trillions of\u00a0bacteria in\u00a0our\u00a0gut\u00a0that keep us healthy. These\u00a0subtle\u00a0changes could\u00a0play a role in how medicines work in\u00a0the body, particularly when treatments are taken together.\u00a0<\/p>\n Understanding how drugs interact with gut bacteria could help\u00a0researchers and the MHRA build on the strong existing evidence base around medicine safety,\u00a0better understand\u00a0why some people\u00a0respond differently to the same medicine,\u00a0and\u00a0support the development of\u00a0treatments that are\u00a0even\u00a0safer and\u00a0more\u00a0effective\u00a0over time.\u00a0\u00a0<\/p>\n Dr Chrysi Sergaki,\u00a0senior\u00a0author of the study and Head of Microbiome at the MHRA, said:\u00a0<\/p>\n \u201cAntibiotics are well known to affect gut bacteria, but this review shows that\u00a0some\u00a0other common medicines can also influence the microbiome. Building this understanding helps us\u00a0identify\u00a0where better data could improve drug development and, ultimately, patient\u00a0care \u2013 while also supporting the responsible use of antibiotics.\u00a0<\/p>\n \u201cThese findings could help researchers understand why some patients respond differently to the same treatment, and why certain side effects occur in some people but not others.\u201d\u00a0\u00a0<\/p>\n The gut microbiome \u2013 the community of trillions of bacteria that live in the digestive system \u2013 plays a key role in immunity and metabolism. While the effects of antibiotics on this balance are well established, the review highlights evidence that several non-antibiotic medicines may have similar, if more subtle, effects.\u00a0\u00a0<\/p>\n For example, the review\u00a0highlights\u00a0that:\u00a0<\/p>\n Metformin, a widely used diabetes medicine, alters gut bacteria in ways that may contribute to both its benefits and some side effects, such as bloating or diarrhoea.\u00a0<\/p>\n<\/li>\n Antipsychotic medicines have been shown in studies to disrupt gut bacteria linked to weight gain and metabolic changes.\u00a0<\/p>\n<\/li>\n<\/ul>\n Better understanding of how medicines affect gut bacteria could also support efforts to\u00a0protect the effectiveness of treatments, including antibiotics.\u00a0The gut is a major home for bacteria\u00a0and other microorganisms, including those carrying resistance genes. When the balance of gut bacteria is disrupted, resistant bacteria can gain an advantage.\u00a0Identifying\u00a0medicines that are less disruptive to the microbiome could, over time,\u00a0help slow the spread of\u00a0antimicrobial\u00a0resistance.\u00a0<\/p>\n Dr Anastasia Theodosiou, co-author of the paper at the University of Glasgow, said:\u00a0<\/p>\n \u201cThis paper is\u00a0an important step\u00a0towards recognising the microbiome as something we need to protect \u2013 and towards designing and testing medicines that are not only more effective, but also safer for our microbiomes.\u201d\u00a0<\/p>\n The MHRA is working with researchers and innovators to develop\u00a0updated\u00a0standards for studying how medicines affect the gut microbiome \u2013 and other microbiomes, such as the\u00a0vaginal microbiome<\/a>\u00a0\u2013 during drug development, where\u00a0appropriate. The aim is to build consistent, reliable evidence that can be used by regulators and developers alike.\u00a0<\/p>\n The MHRA is also exploring new ways to improve how side effects and interactions between medicines are predicted. This includes:\u00a0<\/p>\n The long-term goal is to develop tools that help doctors understand how combinations of medicines affect people in real life, supporting safer, more effective prescribing that can be\u00a0more closely\u00a0tailored to individual patients.\u00a0<\/p>\n Patients\u00a0should keep taking their medicines as prescribed.\u00a0Do not stop or alter your treatment without speaking to a healthcare professional. If you have any concerns or questions, seek advice from your doctor or pharmacist, and report any suspected side effects via\u00a0the\u00a0Yellow Card scheme<\/a>. \u00a0\u00a0\u00a0<\/p>\n Notes to editors\u202f\u00a0<\/p>\n Publication:\u00a0S. Do Nascimento\u00a0et al. (2025) \u2018Microbiotoxicity: An under-recognised player in drug efficacy, toxicity, and health outcomes\u2019\u00a0Nature npj Antimicrobials and Resistance.\u00a0DOI:\u00a010.1038\/s44259-025-00165-5<\/a>.\u00a0<\/p>\n<\/li>\n The Medicines and Healthcare products Regulatory Agency (MHRA)\u00a0is responsible for\u00a0regulating all medicines and medical devices in the UK by ensuring they work and are acceptably safe. All our work is underpinned by robust and fact-based judgements to ensure that the benefits justify any risks.\u202f\u00a0<\/p>\n<\/li>\n The MHRA is an executive agency of the Department of Health and Social Care.\u202f\u00a0<\/p>\n<\/li>\n\n
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