Tinea capitis, commonly known as gray nails, is a disease caused by fungal invasion of the nails and the nail. It occurs in people who do not pay attention to personal hygiene, who have direct contact with water or chemicals for a long time, who have poor nutrition or whose nails are often traumatized or impacted, who have frequent contact with people with gray nails, and who have some other diseases of the hands and feet that cause nail damage, which may also lead to fungal invasion. Once the nail is infected with fungus, it will lose its original luster, become white in spots or flakes, turn yellow, thicken the nail, crack, become brittle, buckle, and part of it is dirty yellow or black. The nail may also show small white spots on the nail surface or a softening of the nail. Some of these nail infections may also manifest as nail fungus, swelling and pressure on the skin around the nail. Nail fungus is easily contagious and affects the aesthetics and fine hand movements; it can also be a potential source of infection, infecting the skin and others. The thickened and raised nail plate of gray nails often causes bacterial infections in the skin around the nail, resulting in nail fungus, local cellulitis, and in some cases, severe cases of tinea. These serious comorbidities of gray nails are like time bombs that may not appear when you are physically strong, but once your resistance decreases due to work stress, strain, or other serious illnesses, it can take advantage of the situation and cause you problems. This is why nail fungus should be treated promptly. First have a fungal examination to clarify the diagnosis, and then choose the appropriate medication under the guidance of a physician. Prevention: Active treatment of tinea capitis and tinea pedis is the key to preventing nail fungus. Avoid scratching skin lesions on other parts of the body with your hands; develop good hygiene habits, do not wear other people’s shoes and socks, do not use other people’s towels or bath towels, and do not share basins or footbaths with other people. Wash your hands and feet frequently to keep them clean and at the right humidity level. Avoid scratching the affected area with your hands. Keep your mood relaxed and build up confidence to overcome the disease.