Front-loaded diazepam is used to rapidly control agitation in patients with severe alcohol withdrawal syndrome (AWS). Our institution began using front-loaded lorazepam in August 2017 secondary to a nation-wide shortage of intravenous (IV) diazepam. Currently, there are no studies comparing lorazepam to diazepam for frontloading in severe AWS. Retrospective cohort study of all adults presenting to the emergency department with a diagnosis of AWS and prescribed the institution's alcohol withdrawal agitated delirium protocol 8 months pre and post shortage of IV diazepam were eligible inclusion for the study. Of these, 106 patients were front-loaded with diazepam and 70 patients were front-loaded with lorazepam. There was no difference in the mean change in Clinical Institute Withdrawal Assessment of Alcohol Scale, Revised scores 24 h pre and post front-loading in the two groups (-13.9 ± -8.08 vs. -13.1 ± -8.91, p = 0.534). Patients who received front-loaded lorazepam had an increased incidence of ICU-delirium (positive for the Confusion Assessment Method in the ICU: 75% with lorazepam vs. 52.6% with diazepam, p = 0.009) and a higher risk of over-sedation, but this did not reach statistical significance (Richmond Agitation-Sedation Scale score < -1: 32.1% with lorazepam vs. 18.2% with diazepam, p = 0.063). Front-loaded lorazepam was similar to front-loaded diazepam in controlling AWS symptoms. Lorazepam's delayed onset of action should be considered when determining how quickly repeat doses are administered to avoid the potential for adverse drug events. Copyright © 2020. Published by Elsevier Inc.