The whitening of nails may be caused by physiological factors such as low environmental temperature; it may also be caused by pathological factors such as onychomycosis and anemia. 1. Physiological factors: if the patient is in a low temperature environment for a long time, it will lead to vasoconstriction of the blood vessels in the hands, reduce the local blood supply, and make the nails white. 2. Pathological factors: common diseases such as onychomycosis and anemia. (1) Ringworm of the nails: whitening of the nails may be caused by whitening of the nails. If the nail area is infected with red trichophyton, candida and other pathogens, it is easy to induce onychomycosis, so that the patient appears to have white nails, thickened nails, uneven nails and other symptoms. (2) Anemia: Anemia may lead to whitening of nails because of the decrease of red blood cells and hemoglobin content in the patient’s body under the state of anemia, the oxygen-carrying capacity of blood decreases, and the nails belong to the end of the limbs, and the local tissues will suffer from the lack of oxygen and other symptoms, which will lead to the whitening of nails. Nail whitening can be caused by a variety of reasons, it is recommended that patients go to the hospital for a clear diagnosis and standardized treatment under the guidance of the doctor.