ObjectivesStudies have shown the feasibility of short-course antimicrobials in complicated intra-abdominal infection (CIAI) following source control procedure (SCP). This study aimed to compare postoperative complication rates in short-course (5 days) and conventional (7–10 days) duration groups after antimicrobial therapy.MethodsThis was a single-centre, open-labelled, randomised controlled trial conducted in Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India, from July 2017 to December 2019 on patients with CIAI. Patients who were haemodynamically unstable, pregnant and had non-perforated, non-gangrenous appendicitis or cholecystitis were excluded. Primary endpoints were surgical site infection (SSI), recurrent intra-abdominal infection (IAI) and mortality. Secondary endpoints included time till occurrence of composite primary outcomes, duration of antimicrobial therapy, the length of hospital stays, antimicrobial-free interval, hospital-free days at 30 day intervals and the presence of extra-abdominal infections.ResultsOverall, 140 patients were included whose demographic and clinico-pathological details were comparable in both groups. There was no difference in SSI (37% versus 35.6%) and recurrent IAI (5.7% versus 2.8%;P= 0.76); no mortality was observed in either groups. The composite primary outcome (37% versus 35.7%) was also similar in both groups. Secondary outcomes included the duration of antimicrobial therapy (5 versus 8 days;P<0.001) and length of hospitalisation (5 versus 7 days;P= 0.014) were significant. Times till occurrence of SSI and recurrent IAI, incidence of extra-abdominal infection and resistant pathogens were comparable.ConclusionShort-course antimicrobial therapy for 5 days following SCP for mild and moderate CIAI was comparable to conventional duration antimicrobial therapy, indicating similar efficacy.