Objectives <p>Probiotics are live microorganisms consisting of many bacterial species that have immunoregulatory functions. The effectiveness of probiotic administration in conjunction with topical corticosteroid application in oral lichen planus (OLP) treatment was evaluated.</p> Methods <p>Sixty OLP patients were enrolled in this study and divided into two groups. Group 1 (Probiotics’ group): probiotic capsules were administered twice daily, for 4 weeks in addition to topical clobetasol propionate application 0.05% four times daily. Group 2 (Control group): topical clobetasol propionate 0.05% was applied 4 times daily for 4 weeks. Thongprasom criteria, numerical rating scale and candidal load were evaluated.</p> Results <p>Significant reduction in the numerical rating scale as well as Thongprasom scale in the probiotic group when compared to the control group, after 2 and 4 weeks, and more significant reduction was observed after 2 weeks. No difference in the reduction of the candidal load was observed between the two groups, nevertheless, no topical antifungal was used in the intervention group.</p> Conclusions <p>Systemic administration of probiotics as a supplementary treatment with topical corticosteroid was effective regarding the reduction of; pain, Thongprasom scales, and candidal load. However, the effectiveness was more evident after 2 weeks when compared to 4 weeks resulting in: more rapid relief of symptoms, improving quality of life, in addition to their antifungal properties.</p> Trial registration <p>The current study was registered in <i>clinicaltrials.gov (ID: NCT04383236) 6-11-2023</i>.</p>