Chronic pain affects a significant percentage of the population and is defined as pain that lasts beyond the point of healing. People presenting to hospital with acute illness may have underlying chronic pain that can be exacerbated by their presenting condition, even if this chronic pain is not the reason for their admission. While people may tolerate their usual medicine regimen under normal circumstances, small changes in their physical health can rapidly cause issues with their medication such as increased side effects. This article considers how nurses can improve the safety of people experiencing pain who have been admitted to hospital, and outlines when changes in their health might have implications for their prescribed analgesics.