Low blood pressure is what we normally call diastolic blood pressure, and its normal value is 60-90 mm Hg. If the low pressure is less than 60 mm Hg, it may be dangerous. It may cause insufficient blood supply to the brain, heart and other organs due to low blood pressure, resulting in postural hypotension, angina pectoris and syncope. It is also dangerous if the low pressure is greater than 110 mmHg, i.e., the blood pressure is too high, which can lead to spasm of the cerebral artery or even cerebral hemorrhage. Therefore, low and high blood pressure are both dangerous for us. Normally, we should pay attention to monitor our blood pressure more often and keep it within a reasonable range.