A red forehead may be caused by long time pressure, collision, contact dermatitis, nevus erythematosus and so on. 1. Prolonged compression: such as long time with the forehead lying on the table to sleep, or forehead against something, due to long time compression, can cause forehead localized red. 2. Collision: such as being a foreign body collision or forehead collision to the wall, etc., can also cause a red forehead. 3. Contact dermatitis: such as allergy to cosmetics, antipyretic paste allergy, forehead contact with these exogenous substances, acute or chronic inflammatory reaction can occur, which can cause a red forehead, can also be accompanied by itching, burning sensation, swelling and pain and other symptoms. 4. nevus erythematosus: a vascular skin disease that can occur on the forehead, usually at birth, without obvious discomfort, can be treated by laser. There are many other causes of forehead redness, which should be taken seriously, and it is recommended to consult a doctor in time to find out the cause of the disease and follow the doctor’s instructions for further treatment or therapy.