OBJECTIVES: To understand the full impact of a novel treatment, particularly in more subjective symptoms such as pain, capturing information on any additional medication a patient may have taken alongside the study drug is vital. Two major challenges to the accurate recording of this data in global clinical trials have been 1) producing “localisations” of concomitant medications that are applicable and comparable in all countries involved in the study; and 2) moving away from a reliance on retrospective, site-based capture from patients. The aim of this study was to develop and document an easy to use electronic diary solution combined with an appropriately localised medication list. METHODS: An electronic medication diary which allowed for the recording of medication name, route of administration and dosage was developed for a handheld platform, with iterative testing and refinement in users. The solution included a pre-populated, tailored list of the patient’s most common drugs (n = 38), which could be localised on a country-by-country basis (n = 21) following a process for ensuring the appropriateness of the drug name in the local market. RESULTS: The iterative approach to design and development ensured the development of an electronic solution which was user-friendly and intuitive. Over 3 rounds of testing a number of updates were made based on feedback from user relating to the flow of the diary and the training module. Best practice for developing appropriate localised list of concomitant medication involved asking two local experts for feedback using in-country medical databases. CONCLUSIONS: Accurate tracking of concomitant medication usage is an important aspect of assessing the effectiveness of a new treatment. A user-focused electronic diary solution overcomes the limitations of traditional, retrospective approaches to capturing this information. Localisation of the concomitant drug list ensures accurate and comparable data captured across all studies in a trial.