Gray nails and lichen planus belong to two different diseases, their causes, symptoms, treatment methods are not the same. 1. Different causes: gray nails are nail lesions caused by ringworm bacteria that invade the nail plate and the nail bed, which is infectious; lichen planus is an inflammatory skin disease caused by the interaction of immunity, heredity, infection, neuropsychiatric factors, drugs and other factors. 2. Symptoms are different: patients with gray nails usually have no conscious symptoms, but their nails can be cloudy, thickening, separation, atrophy, shedding, and surface unevenness and other symptoms; lichen planus typical lesions for red or purple flat polygonal shiny papules, often accompanied by oral mucous membrane damage. 3. Different treatment methods: (1) gray nails: for patients with distal damaged nail plate <50% and no nail matrix involvement, local medication can be used for treatment, such as commonly used amorolfine with broad-spectrum antifungal activity, most obvious for dermatophytes; secondly, cyclopirox can also be used for topical treatment, which is strong bactericidal and antibacterial for dermatophytes, yeasts and so on. For patients with more serious symptoms, oral terbinafine, itraconazole, can play a systemic antibacterial treatment. (2) lichen planus: lichen planus can be treated with oral or topical glucocorticosteroid medication under the guidance of a doctor, such as prednisone and halomethasone ointment. When gray nails or lichen planus, pay attention to the hospital in time, avoid blindly use their own medicine.