Photodynamic Therapy with 5-Aminolevulinic Acid Versus Topical Corticosteroids in the Treatment of Oral Lichen Planus: A Randomized Clinical Trial with Lesion Site-Specific Analysis

Objective: Oral lichen planus (OLP) is a chronic immune-mediated condition of the oral mucosa, commonly associated with pain and burning sensations that impair quality of life. This study aimed to compare the efficacy of photodynamic therapy with 5-aminolevulinic acid (ALA-PDT) and topical glucocorticosteroids (CT) in the treatment of OLP, considering lesion location on keratinized and non-keratinized mucosa. Materials and Methods: A randomized clinical trial was conducted on 90 patients with histologically confirmed OLP. Participants were allocated to receive either ALA-PDT in addition to novel oromucosal emulgel containing 5% ALA (five weekly sessions) or clobetasol propionate applied twice daily for two weeks. Lesion area, clinical severity (Reticulation, Erythema, Ulceration—REU index), and subjective symptoms (Visual Analog Scale—VAS) were evaluated before treatment, immediately after, and six months after therapy. Results: ALA-PDT achieved significantly greater and more durable reductions in lesion area, REU scores, and VAS values compared to CT, particularly on non-keratinized mucosa (mean lesion reduction from 2.64 to 0.56 cm2 at six months; p < 0.0001). CT therapy showed initial improvement but was followed by relapse at six months. Both treatments were well tolerated, with only mild transient adverse effects reported. Conclusions: ALA-PDT, especially when applied to non-keratinized oral mucosa, provides superior and longer-lasting therapeutic outcomes than topical CT. The application of novel ALA-loaded emulgel enhances treatment efficacy and tolerability, supporting PDT as a promising alternative for OLP management.