A white hair on the face may be due to lack of melanin, trauma or inflammation, lack of trace elements, etc. 1. Lack of melanin: Because the bulb of the hair follicle contains melanocytes, the hair appears black. When the melanocytes in the follicle are missing or dysfunctional and cannot synthesize melanin, the hair appears white due to the lack of melanin. 2. Trauma or inflammation: If there is only one white hair on the face, the most likely cause is due to trauma or inflammation resulting in localized follicle melanocyte damage or loss, or cause melanocyte dysfunction. 3. Lack of trace elements: It is also possible that the lack of certain trace elements, such as copper, can also lead to whitening of the hair, but usually there will be multiple white hairs. If a white hair grows on the face, it is recommended to go to a regular hospital for examination and treatment under the guidance of a doctor.