Commonly prescribed durations of therapy for many, if not most, bacterial infections are not evidence-based. Misunderstandings by clinicians and patients alike influence perspectives on antibiotic use, including duration of therapy and its role in antibiotic resistance. To demonstrate that shorter durations of antibiotic therapy are as efficacious as longer durations for many infections, a systematic review was undertaken of English-language articles by using PubMed to identify articles for inclusion. Additionally, infection-specific guidelines were identified for review of recommendations. Search terms included specific infection types, randomized controlled trial (RCT), duration of therapy, treatment duration, short course, and long course. Only RCTs of single-agent antibiotic therapy for the treatment of bacterial infections in adults were included. Independent data extraction of articles was conducted by two authors by using predefined guidance for article inclusion. In total, 23 RCTs met our criteria for inclusion. All trials compared single-agent antibiotics for a short and long antibiotic course in six common infections: community-acquired pneumonia, ventilator-associated pneumonia, intraabdominal infections, skin and soft tissue infections, uncomplicated cystitis, and complicated cystitis or pyelonephritis. Clinicians can decrease net antibiotic use by recommending shorter courses where evidence supports them. Antimicrobial stewardship programs that systematically address treatment duration may significantly affect institutional antibiotic use without negatively affecting patient care.