Curcumin, a turmeric extract, for oral lichen planus: A systematic review

OBJECTIVE: Conduct a PROSPERO registered (CRD42018105227) systematic review of the efficacy of curcumin in the treatment of oral lichen planus (OLP). DATA SOURCES: Medline from the earliest possible date to the present (December 18, 2018) using the terms "turmeric" OR "curcumin" OR "curcuma" AND "oral lichen planus". STUDY SELECTION AND DATA EXTRACTION: Studies assessing patient outcomes in OLP. There were four trials assessing the comparative efficacy of topical curcumin vs. topical corticosteroids and three trials assessing the efficacy of oral curcumin vs. placebo. DATA SYNTHESIS: Clinical and methodological heterogeneity precluded statistical pooling. There were many limitations in the literature weakening the strength and applicability of evidence. Topical curcumin provided reductions in pain, burning, and clinical manifestations of OLP versus baseline, effects similar or inferior to topical corticosteroids. In oral curcumin trials, there were no significant benefits of curcumin therapy versus placebo but there were some potential benefits and reasonable safety in an observational extension study. CONCLUSIONS: It is difficult to determine whether topical or oral curcumin is a viable therapy for oral lichen planus. Topically applied curcumin in particular shows promising preliminary data but would likely not supplant topical corticosteroids as the modality of choice for most patients.