Usually, the normal standard for blood pressure is a systolic range of 90 to 140 mmHg and a diastolic range between 60 and 90 mmHg. If the blood pressure is slightly higher than the upper limit of systolic or diastolic blood pressure in a short period of time, it may be due to strenuous exercise, emotional excitement, mental tension, etc.. If the blood pressure is elevated for a long period of time it may be due to hypertension, which may cause headache, dizziness, numbness of limbs, chest tightness and other symptoms. If the blood pressure is lower than the lower limit of systolic or diastolic blood pressure, it may be due to severe infection, massive blood loss, allergy, dehydration, etc., leading to a drop in blood pressure. The patient may experience symptoms such as lack of concentration, fatigue, and fear of cold. In addition, if the patient’s blood pressure is abnormal, it is recommended to go to the hospital in time to avoid delay.