The sudden appearance of light brown spots on the face is usually seen as melasma or age spots. Sex hormone level, ultraviolet radiation, genetic factors and ageing are the main causes of the disease. 1. Melasma: It is a relatively common pigmentation spot, mainly manifested as light brown or yellowish symmetrical pigmentation on facial skin. Abnormal level of sex hormone secretion, ultraviolet radiation and genetic factors are the main causes of melasma. 2. Age spots: it is a kind of normal degenerative skin lesion, which mainly manifests as brown patches on the facial skin and back of the hands of the elderly, with obvious hyperkeratosis or seborrheic scabs on the surface, and the pathogenic factors mainly include ageing, ultraviolet irradiation and hereditary factors. For the light brown spots on the face, it is recommended to go to a regular hospital in time, ask the doctor to conduct an interview, and then analyze the treatment according to its clinical manifestations.