The goal of this clinical trial is to assess the efficacy of different formulations of the drug tacrolimus in treating patients with oral lichen planus. The main questions it aims to answer are:

• Does the nanoencapsulation of tacrolimus in an aqueous solution, used as a spray, improve the effectiveness of treating oral lichen planus lesions compared to the commercially available tacrolimus ointment?
• Which tacrolimus formulation can keep participants free of lesions for longer periods?

Researchers will compare a spray of 0.08% tacrolimus nanoencapsulated aqueous solution against a 0.1% free tacrolimus commercial ointment to determine which formulation is more effective.

Participants will:

• Apply one of the proposed tacrolimus formulations twice a day for 1 month.
• Visit the clinic once every 2 weeks for checkups and tests, with follow-ups extending up to 3 months.

Inclusion Criteria:

• individuals with a clinical and histopathological diagnosis of erosive/ulcerative/atrophic and symptomatic oral lichen planus, according to the criteria established by the American Academy of Oral and Maxillofacial Pathology

Exclusion Criteria:

• History of oral cancer;
• history of allergic reactions to tacrolimus or any other component of the formulas;
• history of organ transplant or have a systemic condition that induces significant immunosuppression;
• be pregnant or lactating.