Gray nails, also known as onychomycosis, are caused by fungal infections and have no significant correlation with vitamin deficiency. Vitamin deficiency can cause symptoms of nail dystrophy such as localized dry, pale skin and rough, bloodless nail edges, resulting in nail changes that resemble gray nail-like changes. In addition to discoloration of the nail plate, gray nails may also manifest as cloudy, thickened, separated, atrophied, peeling, buckling, uneven surface, etc. Pain and bleeding under the nail may also occur. Patients need to go to the dermatology department of the hospital for identification. The diagnosis of gray nail or nail dystrophy can be made through fungal smear microscopy and fungal or trace element tests. If the nail dystrophy is caused by vitamin deficiency, the patient will need to take appropriate vitamin supplements. If the patient is diagnosed with gray nails, he or she should take oral antifungal treatment with terbinafine or itraconazole, or topical treatment with terbinafine ointment or sertaconazole ointment. If necessary, nail extraction or removal of the diseased nail is required. Laser and photodynamic therapy can also be used as an adjunct and alternative treatment for gray nails.