Gray nail is caused by fungal infection, the initial manifestation is the appearance of irregular small white spots on the side edge of the nail, and then turn into lusterless gray spots, and gradually become yellowish brown until black. Gray nail development time is longer, the specifics vary from person to person: 1, the formation period: the formation period of gray nails generally need 2 months, or even longer, for some patients with strong resistance, the formation period may also be extended to about half a year; 2, the treatment period: gray nails tend to be more slow progress, the treatment cycle is also longer. From the beginning to the end of the onset, usually finger gray fingernails need 2-3 months, toe gray fingernails need 3-4 months. Patients should go to the hospital in time if they realize the abnormalities, conduct microscopic examination of nail fungal smears and culture of fungi, make a clear diagnosis, and then follow the doctor’s instructions to actively carry out the treatment. At present, the clinical usually use oral terbinafine, itraconazole for antifungal treatment, can also choose bifonazole solution and other topical treatment. In severe cases, nail extraction or nail removal is required. In addition, laser therapy and photodynamic therapy can be used to inhibit pathogenic bacteria and kill microorganisms. If left untreated, gray nails cannot be cured for years.