The common causes of forehead numbness are high blood pressure, ischemic stroke, skin allergies and so on. 1. Hypertension: the main manifestation of the flow of blood on the walls of blood vessels pressure value is persistently higher than normal, which can lead to vasospasm, the phenomenon of insufficient blood supply to the scalp, resulting in the symptoms of numbness of the forehead, but also head swelling and pain, paroxysmal dizziness symptoms. 2. Ischemic stroke: mainly due to intracranial arteriosclerosis, stenosis and occlusion, or thrombosis. Patients may show numbness in the forehead, accompanied by weakness or numbness of unilateral limbs or face, crooked mouth, slurred speech and other symptoms. 3. Skin allergies: If the forehead is exposed to allergic substances, such as poor quality cosmetics, pollen, etc., an allergic reaction will cause the patient to appear local skin sensory abnormalities, which can also be manifested as numbness of the forehead. If the phenomenon of forehead numbness, it is recommended to consult a doctor in time, clear diagnosis and active treatment.