Augmentative and alternative communication (AAC) has been used by patients with acquired expressive communication disorders as an alternative to natural speech. The use of symbols to express pain, which is intangible, is challenging because designing a series of comprehensible symbols to represent personal experiences such as pain is not straightforward. This study describes (a) the development of symbols to express pain that were derived from Chinese pain-related similes and metaphors for an AAC mobile application developed specifically for this study known as PainDiary and (b) an assessment of the appropriateness of the app compared to conventional methods of collecting pain information. The symbols depicted headache pain and discomfort, which is prevalent among neurosurgical patients. The participants were 31 patients diagnosed with acquired expressive communication disorders who were receiving treatment in a neurosurgery general ward of Chang Gung Memorial Hospital in Taiwan and 14 nurses who worked on the ward. Pain information was collected by nurses using conventional methods and the PainDiary app. Assessment data, including the accuracy and efficiency of and user satisfaction with PainDiary, are compared. The results show that use of the app was effective in reporting pain and that patients required less time to report a pain event. The results further indicate that the PainDiary app was better received by younger individuals than by their older counterparts.