The redness of the forehead skin may be related to physiological factors, followed by seborrheic dermatitis, capillary dilatation and solar dermatitis and other diseases. 1. Physiological factors: such as hand rubbing, emotional excitement, hot weather, etc., may trigger skin redness. 2. Seborrheic dermatitis: the cause of the disease is related to age, heredity, neurological dysfunction and other factors, most commonly found on the scalp, face and other places, the skin will appear red spots, flaking and other symptoms. 3. Capillary dilatation: its cause is more complex, may be related to the environment, physical and genetic factors, patients are mostly manifested as skin erythema, such as dots, starbursts and spots, mostly in the face. 4. Solar dermatitis: clinical manifestations of bright red skin erythema, blisters and other symptoms, mostly in the face and other places. The cause of the disease is mostly related to excessive ultraviolet radiation. The causes of forehead skin redness are more reasons, in the exclusion of physiological factors, it is recommended that patients seek medical examination to clarify the cause of the disease.