Abstract Aims In ‘nil by mouth’ (NBM) emergency surgery patients, to 1) reduce the proportion of oral medications incorrectly administered/omitted and 2) reduce the proportion that are fasted for longer than the recommended 6 hours for food and 2 hours for clear fluids. Methods Medication administration and fasting data were collected prospectively on patients who received emergency surgery over two 2-week periods (n=169). Between these rounds of data collection, interviews were conducted with a range of staff members to understand reasons for poor compliance with guidelines. Based on this, local guidelines were updated to reflect a wider range of medications, and a range of methods were used to educate staff about best practice. Results In the first round of data collection, 45% of drug administration decisions were not compliant with guidelines. By the second round, these drug errors were reduced by 60%. On average fasting times were reduced by 25%, from 14.4 hours to 10.9 hours for clear fluids and from 24.2 hours to 18.5 hours for food. However, in both rounds, the range of times exceeded 110 hours. Conclusions Education about ‘NBM’ can significantly improve preoperative optimisation of patients and reduce the risk to patient safety associated with critical medications being omitted. The reduction in medication errors was so significant because lack of understanding of guidelines was highlighted as the major cause of non-compliance. Impact on fasting times was smaller, likely due to the other factors contributing to the prolonged times, such as patient choice, operation scheduling difficulties, and inadequate communication between teams.