Gray nails are caused by a fungal infection and initially appear as small irregular patches of white on the lateral edge of the nail, which then turn into lusterless gray spots and gradually turn yellowish brown until black. The development of gray nails takes a long time, and the details vary from person to person: 1. Formation period: The formation period of gray nails usually takes 2 months or even longer, and for some patients with strong resistance, the formation period may also be extended to about half a year; 2. Treatment period: Gray nails tend to progress more slowly, and the treatment period is longer. From the beginning to the end of the onset, it usually takes 2-3 months for finger gray nails and 3-4 months for toe gray nails. Patients who feel abnormal should go to the hospital promptly, have a fungal smear microscopy of the diseased nail and culture the fungus, and then follow the doctor’s instructions for active treatment after a clear diagnosis. At present, the clinic usually uses oral terbinafine, itraconazole for antifungal treatment, but also can choose bifenazole solution and other topical treatment. In severe cases, nail extraction or removal of the diseased nail is required as prescribed by the doctor. In addition, laser treatment and photodynamic therapy can be used to inhibit pathogenic bacteria and kill microorganisms. If left untreated, gray nails cannot be cured for years.