Effect of Probiotics on Oral Candida Colonization in Patients with Oral Lichen Planus: A Systematic Review

Abstract

Background: Oral Lichen Planus (OLP) is a chronic immune-mediated inflammatory disorder of the oral mucosa, affecting middle aged women. Despite increasing interest in probiotics as adjunctive therapy in OLP, evidence regarding their role in reducing oral Candida colonization and improving clinical outcomes remains limited. This review was done to systematically evaluate the effect of probiotic therapy on oral Candida colonization, recurrence of candidiasis, and related clinical outcomes in patients with oral lichen planus. Materials and Methods: A systematic review of randomized controlled trials was conducted following the PRISMA 2020 
guidelines and registered with PROSPERO (CRD42024550624). Electronic searches were performed across multiple databases from January 2001 to March 2025. Trials assessing probiotic interventions with reported microbiological outcomes, including Candida load, recurrence, or fungal colonization, were included. Risk of bias was assessed using the Cochrane RoB 2 tool with domain-level judgments, and certainty of evidence was evaluated using the GRADE approach. Results: Four randomized controlled trials (RCTs) involving 110 participants were included, of which two specifically reported oral Candida-related outcomes. Considerable heterogeneity existed in probiotic strains, formulations, treatment regimens, and outcome measures. Probiotic monotherapy did not demonstrate consistent reduction in oral Candida colonization or recurrence when compared with placebo or standard therapy. In contrast, adjunctive probiotic use alongside topical corticosteroids was associated with a greater reduction in oral Candida colonization, decreased risk of steroid-associated candidiasis, and improved microbial balance. Secondary benefits included greater pain reduction and improved lesion scores in some studies. Immunological assessments showed non-significant trends toward reduced inflammatory markers. All probiotic interventions were well tolerated, with no serious adverse events reported. Conclusion: 
Probiotics do not appear to provide consistent clinical benefit as monotherapy for reducing oral Candida colonization in patients with oral lichen planus. However, their adjunctive use alongside topical corticosteroids may offer supportive benefits by reducing oral Candida load, improving microbial homeostasis, and enhancing treatment tolerability, particularly in patients at risk of steroid associated candidiasis.