Setting a low quantity of opioid tablets as the default option in electronic medical record prescribing orders may “nudge” clinicians to prescribe fewer opioids. When two emergency departments implemented a 10-tablet default instead of a manual entry, the proportion of 10-tablet prescriptions written more than doubled, from 20.6% to 43.3%. Conversely, 20-tablet prescriptions decreased from 22.8% to 16.1%, and prescriptions for 11-19 tablets decreased from 33.5% to 20.1%.