Lichen planus eventually goes away on its own, but treatment or removal of the trigger can ease symptoms and clear up the rash quickly. The main treatment is steroid medications that are rubbed on, injected, or taken by mouth. Retinoid medications used for acne may also help. Antihistamines (such as Benadryl) or soothing baths can help the itching. Sometimes doctors use a type of ultraviolet light therapy called PUVA (psoralen plus UVA radiation), narrow band UVB phototherapy, or antibiotics.