Short-course antibiotic therapy yields comparable clinical and bacteriological success for adults with community-acquired pneumoniaShorter antibiotics work just as well for pneumonia

BackgroundOptimizing antibiotic duration for community-acquired pneumonia (CAP) is a critical priority for global antimicrobial stewardship. While short-course therapies (≤5 days) show clinical promise, robust, updated evidence comparing their specific safety profiles, particularly regarding severe adverse events, against traditional long-course regimens (>5 days) is required to reliably guide clinical practice.MethodsFollowing the PRISMA 2020 guidelines (PROSPERO: CRD420261278947), we systematically searched PubMed, Embase, and CENTRAL up to January 15, 2026, for randomized controlled trials (RCTs) comparing short-course (≤5 days) and long-course (>5 days) antibiotic therapies in adults with CAP. The primary outcome was clinical success. Secondary outcomes included bacteriological and radiological success, mortality, treatment discontinuation, and a detailed profile of adverse events (AEs).ResultsA total of 21 RCTs were included. Short-course antibiotic therapy achieved comparable efficacy to long-course therapy in clinical success (RR = 1.00, 95% CI: 0.98–1.02, p = 0.77), bacteriological success (RR = 1.00, 95% CI: 0.97–1.03, p = 0.86), radiological success (RR = 1.03, 95% CI: 0.97–1.09, p = 0.29), all-cause mortality (RR = 0.79, 95% CI: 0.47–1.32, p = 0.37), and treatment discontinuation (RR = 0.95, 95% CI: 0.68–1.31, p = 0.74). While short-course regimens were associated with a marginally higher risk of mild treatment-related AEs (RR = 1.12, 95% CI: 1.00–1.26, p = 0.04), they showed a non-significant downward trend in treatment-related serious adverse events (SAEs) (RR = 0.37, 95% CI: 0.13–1.07, p = 0.07). Most included studies demonstrated generally acceptable methodological quality with an overall low risk of bias.ConclusionShort-course antibiotic therapy yields comparable clinical, bacteriological, and radiological efficacy for adults with CAP, with a favorable safety trend for severe adverse events. By maintaining equivalent efficacy while reducing cumulative antibiotic exposure, this regimen aligns with global antimicrobial stewardship priorities and provides robust evidence to support shortened antibiotic duration as a standard approach for appropriately selected adult CAP patients.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/view/CRD420261278947, identifier CRD420261278947.