Half of the face red half of the face is not red may be caused by facial pressure, local capillary expansion, ultraviolet radiation, skin allergic reaction. 1. Facial pressure: when the face is subjected to localized pressure, such as sleeping often take the side lying position, etc., will make the blood flow of our face is not smooth, thus leading to half of the face red half of the face is not red, at this time, generally do not need to be dealt with, relieve the pressure can be restored to normal after a period of time. 2. Local capillary dilatation: when one side of the face is traumatized such as bumps and bruises, it will make the rich capillaries of the face dilate and thicken, thus leading to the occurrence of half of the face red and half of the face red, at this time, you can immediately use ice packs for the patch to help alleviate the symptoms, and after 48 hours of injury, you can use a hot towel to help improve the symptoms of hot compresses. 3. Ultraviolet radiation: when one side of the facial skin is exposed to excessive ultraviolet radiation, while the other side is exposed to less ultraviolet radiation, may also lead to half of the face red and half of the face does not red, so it is recommended to go out and do a full range of sunscreen measures, in order to prevent the face of the skin by ultraviolet radiation damage. 4. contact dermatitis: when one side of the facial skin in contact with pollen, dust mites and other allergens, may lead to allergic reactions to the facial skin of people with allergies, resulting in half of the face red half of the face does not red phenomenon occurs, such patients can be coated with local anti-allergy drugs (such as Benadryl) to help improve the allergy symptoms. To summarize, it is recommended that half of the red face and half of the face is not red in time to clarify the cause of the disease, active treatment, to avoid further aggravation of the condition. The medication should be used according to the doctor’s instructions.