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General antibiotics (unspecified)
medication Under reviewBroad-spectrum antibiotics are pharmaceutical agents that kill or inhibit a wide range of bacteria, including both Gram-positive and Gram-negative species. They are typically used when the specific causative organism of an infection is unknown or when polymicrobial infections are suspected. Common examples include amoxicillin–clavulanate, doxycycline, fluoroquinolones, clindamycin, piperacillin–tazobactam, and trimethoprim–sulfamethoxazole. These drugs work through diverse mechanisms such as inhibiting bacterial cell wall synthesis, blocking protein synthesis, or interfering with DNA replication, leading to bacterial death or growth arrest. While they are lifesaving for serious infections, broad-spectrum antibiotics also affect commensal bacteria throughout the body, especially in the gut and on the skin. This widespread impact can alter microbiome composition, reduce microbial diversity, and favor the emergence and persistence of antibiotic-resistant strains. In healthy individuals, short courses of broad-spectrum antibiotics do not confer performance or wellness benefits and are not used as a health-promoting supplement. Instead, they are prescribed for treatment or prevention of bacterial infections, with growing recognition that even brief exposure can produce measurable and sometimes long-lasting changes in microbiome structure and antimicrobial resistance patterns.
Research summary
Controlled studies in healthy volunteers show that short courses of broad-spectrum antibiotics can markedly reduce gut and skin microbial diversity, alter the relative abundance of key bacterial groups, and promote the selection and persistence of antibiotic-resistant strains. These microbiome changes can appear within days of exposure and may persist for months or even years, depending on the drug class, dose, and duration of therapy. Evidence from randomized trials, observational cohorts, and meta-analyses indicates that although systemic innate immune responses to acute endotoxin challenge may remain intact after antibiotic-induced microbiota disruption in healthy adults, the individual-level risk of carrying antibiotic-resistant bacteria increases after primary care prescriptions, with the highest risk in the first month and residual effects detectable up to 12 months. Large population data also suggest that repeated or long-term antibiotic use is linked to sustained reductions in gut microbiome diversity over several years, which may contribute to higher risks of metabolic and cardiovascular diseases. Overall, the research consensus is that broad-spectrum antibiotics should be used judiciously due to their significant impact on the microbiome and resistance, especially in otherwise healthy people.
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Impact of commonly prescribed antibiotics on gut microbiota in healthy adults (MIME Study trial description)
Study team (MIME Study)
Effect of antibiotic prescribing in primary care on antimicrobial resistance in individual patients: systematic review and meta-analysis
C. Costelloe, D. Metcalfe, A. Lovering, D. Mant, A. Hay
Alterations of human skin microbiome and expansion of antimicrobial resistance after systemic antibiotics.
L. A. Peterson, C. R. Pasolli, C. D. Wheeler, et al.
No reports yet
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Add General antibiotics (unspecified) to your stack to report effects
Impact of commonly prescribed antibiotics on gut microbiota in healthy adults (MIME Study trial description)
Study team (MIME Study)
Alterations of human skin microbiome and expansion of antimicrobial resistance after systemic antibiotics.
L. A. Peterson, C. R. Pasolli, C. D. Wheeler, et al.
Antibiotic use and gut microbiome composition links from individual-level prescription data of 14,979 individuals.
T. Vatanen, A. R. S. W. P. Kurilshikov, et al.
Research (4 studies)
Antibiotic use and gut microbiome composition links from individual-level prescription data of 14,979 individuals.
T. Vatanen, A. R. S. W. P. Kurilshikov, et al.
Alterations of human skin microbiome and expansion of antimicrobial resistance after systemic antibiotics.
L. A. Peterson, C. R. Pasolli, C. D. Wheeler, et al.
Impact of commonly prescribed antibiotics on gut microbiota in healthy adults (MIME Study trial description)
Study team (MIME Study)
Effect of antibiotic prescribing in primary care on antimicrobial resistance in individual patients: systematic review and meta-analysis
C. Costelloe, D. Metcalfe, A. Lovering, D. Mant, A. Hay
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