High pressure is systolic blood pressure, below 90mmHg can be seen in physiological reasons, a mild reduction is not harmful; can also be seen in pathological reasons, can lead to ischemia and even functional failure of the brain, heart, kidneys and other organs and tissues. Systolic blood pressure lower than 90mmHg should be considered low blood pressure, part of the population belongs to physiological reasons, manifested as somatic hypotension, the patient may not have any clinical manifestations, mostly seen in thin women or the elderly, without special treatment. If the hypotension is pathologic, such as heart disease, shock caused by various reasons, low systolic blood pressure will lead to insufficient cerebral perfusion, which can be manifested as symptoms of dizziness, can also be accompanied by nausea and vomiting, and serious or even coma may occur. Low systolic blood pressure can also lead to insufficient myocardial perfusion, reflex accelerated heart rate, the patient may have symptoms of chest tightness, and even severe shock. Low systolic blood pressure can also lead to insufficient perfusion of the kidneys, may appear to reduce urine output, or even acute renal failure. Low systolic blood pressure, if accompanied by obvious symptoms, should promptly go to the hospital, under the guidance of the physician for treatment.