The causes of sudden dizziness and lightheadedness may be hypertension, transient insufficiency of blood supply to the brain, syncope and so on, as follows: a. Hypertension: Hypertension is a common cause of dizziness and lightheadedness, especially after more emotional excitement, or strenuous exercise, blood pressure will suddenly rise. If the blood pressure is high, it is recommended that you can take antihypertensive drugs to relieve. Second, the brain transient insufficient blood supply: patients may be squatting toilet or squatting for too long, suddenly stand up, can also appear dizziness, dizziness. This is due to a sudden change in position, resulting in a transient lack of blood supply to the brain, which can lead to dizziness and blurred vision, it is recommended that when standing up must be slow. Third, syncope: due to prolonged standing for too long, resulting in low blood pressure and insufficient cerebral perfusion, dizziness and dizziness can also occur.