The causes of high and low blood pressure may be uncontrolled hypertension triggers, irregular medication or secondary hypertension. In normal people or hypertensive patients after standardized treatment, blood pressure fluctuates throughout the 24 hours of the day, often in an aryeplastic pattern: generally the first peak of blood pressure is high in the morning, the second peak in the afternoon and lower than the morning peak, and slightly lower in the evening. It also fluctuates throughout the year, with low blood pressure in summer due to dilated blood vessels and sweaty skin, and high blood pressure in winter due to constricted blood vessels. These are fluctuations within the normal range, also known as physiological fluctuations in blood pressure. Changes in blood pressure beyond this range are seen in the following cases: 1, uncontrolled triggers of elevated blood pressure: such as staying up late, addiction to smoking, alcohol, overeating, excessive dieting, uncontrolled blood sugar, emotional instability, irritability, heatstroke, dehydration, etc., can induce rapid changes in blood pressure within a short period of time. 2, medication is not standardized: blood pressure is normal, stop taking medication, blood pressure rises and then take medication, this kind of jump medication, will lead to a big rise and fall in blood pressure. Anti-hypertensive drugs need to be taken continuously and regularly in order to lower blood pressure smoothly. Most antihypertensive drugs should be taken on an empty stomach, and some slow-release and controlled-release dosage forms of drugs, such as nifedipine controlled-release tablets, should not be broken or chewed. In addition, if hypertensive patients are taking short-acting antihypertensive drugs, due to the short half-life of short-acting antihypertensive drugs, antihypertensive effect maintenance time is short, which may lead to high and low blood pressure, fluctuations are relatively large. Therefore, it is recommended to take long-acting antihypertensive drugs. 3, secondary hypertension: most secondary hypertension causes will prompt a temporary or sustained increase in blood pressure, and the magnitude of the increase in blood pressure is large, patients generally have accompanying symptoms, the effect of conventional antihypertensive drugs control is not good. Excessive fluctuations in blood pressure within a short period of time may cause serious adverse consequences, such as acute myocardial infarction, acute heart failure, acute renal failure, cerebral hemorrhage, cerebral infarction, aortic coarct, hypotensive shock and other malignant events, with a very high rate of disability and death, so timely consultation is required.