Personalized dose optimization is desirable to improve subjective well-being and support rehabilitation. Therefore, N = 1 trials investigating tools to self-manage functional outcomes during dose optimization are necessary. The aim of this pilot study was to determine in two N = 1 trials whether an experience sampling method (ESM) smartphone app could be used to monitor and detect changes in subjective well-being and psychotic experiences during and after dose reduction. Two participants with a psychotic disorder in remission underwent gradual dose reduction under a longitudinal self-monitoring paradigm, accompanied by regular clinical monitoring by the attending physician. Subjective well-being was monitored with an (ESM) app through momentary affective experience (positive and negative affect) and physical well-being (tiredness, feeling unwell, and pain). Momentary psychotic experiences were assessed with four items. Time-series linear regression models were used to detect changes in reduction phases compared to baseline. Whereas significant improvements in subjective well-being and psychotic experiences during dose reduction were detected in one participant, the opposite was demonstrated for the other participant, showing worsened subjective well-being and increased psychotic experiences in the reduction phase compared to baseline. Self-monitoring with an ESM smartphone app offers a tool for detecting changes in subjective well-being and psychotic experiences during antipsychotic dose reduction. In this way, ESM may increase an individual's sense of control and empowerment. It may further facilitate dose optimization and shared decision-making at an individual level, which is required considering the high heterogeneity in psychotic disorders. (PsycInfo Database Record (c) 2024 APA, all rights reserved).