Gray nails, also known as onychomycosis, are caused by a fungal infection 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 edges of the nails, resulting in nail changes similar to gray nail-like changes. In addition to the discoloration of the nail plate, gray nails may also manifest as cloudy nail plate, thickening, separation, atrophy, detachment, buckling, uneven surface, etc. Pain and under-nail bleeding may also occur. Patients need to go to the dermatology department of the hospital for identification, which can be done through microscopic examination of fungal smears of diseased nails, laboratory tests for fungi or trace elements, to clearly diagnose whether it is gray nails or nail dystrophy, and the doctor usually chooses the appropriate treatment plan for the patient according to the different causes of the disease. If the nail dystrophy is caused by vitamin deficiency, the patient needs to take appropriate vitamin supplements. If gray nails are diagnosed, the patient should take oral antifungal treatment with terbinafine and itraconazole, as well as topical treatment with terbinafine ointment and sertaconazole ointment, etc. If necessary, nail extraction or nail dystrophy may be required. Nail extraction or nail removal is required if necessary. Laser and photodynamic therapy can also be used as adjunctive and alternative treatments for gray nails.