The common causes of high blood pressure and low blood pressure are physiologic factors, primary hypertension and other diseases. 1. Physiological factors. For example, emotional excitement, strenuous exercise, drinking alcohol and so on, can cause sympathetic nerve excitement, thus causing high pressure and low pressure are high. 2. Primary hypertension. The cause of the disease is unknown, may be related to genetic, obesity, smoking, long-term late night, long-term consumption of too salty or high fat content of food and other factors. 3. Other diseases. Can cause secondary high pressure and low pressure are high. Commonly, there are renal diseases such as glomerulonephritis, chronic pyelonephritis, endocrine diseases such as pheochromocytoma, aldosterone tumor, cardiovascular diseases such as aortic constriction, aortic insufficiency, and so on, such as hypertension in pregnancy, erythrocytosis and so on. The presence of high pressure and low pressure are high, you should consult a doctor in time to clarify the cause of the disease and timely treatment.