It is estimated that 1 in 10 hospital inpatients in Scotland have experienced a medication error. In our unit, an audit in 2019 identified documentation of as-required prescriptions on drug Kardexes as an important target for improvement. This project aimed to reduce the percentage of these errors to <5% in the ward in 6 months.Weekly point prevalence surveys were used to measure medication error rates over a 12-week baseline period. Errors in route, frequency of dose and maximum dose accounted for >80% of all prescribing errors. The intervention was a poster reminder about the three most common errors linked to standards for prescribing pain medication. Barriers to change were identified through inductive thematic analysis of semistructured interviews with five ward doctors and two staff nurses.In the 6 weeks after intervention, our run chart showed a shift in maximum dose errors per patient, which fell from 75% to 26%. However, route and frequency errors remained high at >70% per patient. Most of these errors were due to use of abbreviations, and qualitative interviews revealed that senior doctors and nurses believed that these abbreviations were safe. We found some evidence from national guidelines to support these beliefs.Overall, the intervention was associated with decreased prevalence of patients without a maximum dose written on their prescription, but lack of space on drug prescriptions was identified as a key barrier to further improvement in both maximum dose and abbreviation errors.