OBJECTIVE: The objective of this study was to investigate the effect of topical morphine on erosive/ulcerative lesions in patients with oral lichen planus (OLP). Previous studies reported on an enhanced remission of skin wounds when morphine was applied topically. MATERIALS AND METHODS: This was single-center, prospective, double-blind, placebo-controlled, randomized, multi-arm (3), phase II study (RCT). Patients diagnosed with erosive and/or ulcerative OLP applied 0.2 or 0.4 mg morphine dissolved in glycerine, three times a day for 5 days. The primary outcome was the extent of healing. Secondary outcomes were as follows: (1) effect on pain, (2) presence and severity of opioid-related central and local side effects, (3) whether patients required 'rescue medication' for treatment of pain, and (4) total intake of test substance. RESULTS: A total of 123 patients were screened for eligibility, 45 patients were recruited into the study, and 43 completed it. Patients applied a solution of either placebo or 0.2 or 0.4% morphine in groups of n = 12, n = 15, and n = 16, respectively. Extent of healing was similar in the three groups. Severity of pain was minor pre-treatment and throughout the course of the study. Only minor adverse events were reported (dry mouth, burning sensation). CONCLUSION: Morphine did not enhance wound healing compared to placebo-treated patients. Healing was observed in all groups, which may be attributed to an effect of glycerine or to the natural course of the disease. Patients experienced only mild levels of pain, rendering the model insensitive for assessing pain. CLINICAL RELEVANCE: OLP is a chronic disease and current treatment options are limited. Healing occurred in all three study groups, an effect we attribute to the carrier.