Abstract Objective To develop green banana peel (Musa sapientum) powder for the treatment of peristomal dermatitis, and to evaluate its effectiveness and healing time. Methods A clinical, analytical and longitudinal study. In total, 44 volunteers of both genders, aged > 18 years, with intestinal ostomy, who presented peristomal dermatitis, participated in the research. The sample was divided into two groups: the study group used a powder containing 10% of green banana peel, and the control group used ostomy powder. The research was approved by the Ethics in Research Committees (Comitês de Ética em Pesquisa, CEP, in Portuguese) under opinion n° 2.381.904. Results The healing time of the study group was shorter than that of the control group (p = 0.022). To analyze the results, we used the two-sample t-test (mean days until healing for both study groups). Conclusion The powder containing 10% of green banana peel was developed, and effective healing of the peristomal dermatitis was observed. Compared to the ostomy powder, it presented a shorter healing time.