Clostridioides difficile infection guidelines were published in final format on April 1, 2018. Among 4962 and 3545 C. difficile infection cases in children the year before and after publication, oral metronidazole use decreased from 63.0% to 44.3% (P < 0.001) and oral vancomycin use increased from 27.3% to 47.7% (P < 0.001). Quarterly metronidazole utilization decreased postguidelines among 117 institutions, incidence rate ratios 0.86 (95% confidence intervals: 0.78-0.96).