Severe gray nails are primarily treated with antifungal medications. Gray nails, scientifically known as onychomycosis, are lesions caused by infection of the nail plate by dermatophytes and other pathogenic fungi. For severe gray nails, oral antifungal medications such as terbinafine, itraconazole, and fluconazole can be taken. Oral medication often requires a longer course of treatment, usually around three to four months. In order to shorten the course of the disease and increase the efficacy of treatment, you can add the use of topical drug treatment, such as 5% amorolfine nail application, which can significantly improve the cure rate, shorten the treatment time and reduce adverse reactions. Patients with onychomycosis should go to the hospital and use the medication under the guidance of a physician.