Gray nail is a disease caused by dermatophytes invading the nail plate or subnail tissue, clinically known as onychomycosis. Itraconazole belongs to broad-spectrum antifungal drugs, which can be used for both deep fungal infections and superficial fungal infections, and it is the most effective drug for the treatment of gray nails in clinic at present, and itraconazole shock therapy is usually used. Because itraconazole has liver and kidney toxicity, it is necessary to check the liver and kidney function before implementing the treatment, and patients with liver and kidney function impairment should not use itraconazole to treat gray nails. This therapy has a long treatment period, usually takes more than 3-6 months to completely cure gray nails, during the treatment period, we should regularly review the liver and kidney function, usually pay attention to a light diet, balanced nutrition, eat more vegetables and fruits, do not share shoes and socks with other people, shoes and socks with hot water to iron and wash.