Elderly people with high and low blood pressure may be caused by physiological factors such as drinking strong tea and emotional changes, or it may be caused by pheochromocytoma and not taking antihypertensive drugs regularly. 1. Physiological factors: (1) Normal phenomenon: blood pressure within a day is not fixed, normal blood pressure exists in circadian rhythm, blood pressure may be higher in the morning and lower at night, which is a normal physiological phenomenon. (2) Lifestyle habits: Blood pressure may rise when exercising, drinking strong tea, alcohol, or being overly nervous, and then fall when these factors are removed. (3) Change of body position: The blood pressure value varies with different body positions, especially when the blood pressure suddenly changes from sitting, lying down or squatting to standing upright, the blood pressure will drop significantly. (4) Psychological factors: With the change of psychological pressure and emotion, the blood pressure of the elderly will also appear high and low. (2) Pheochromocytoma: patients with pheochromocytoma may paroxysmally secrete excessive catecholamines and other hormones, which will increase the blood pressure, and when the secretion is less, the blood pressure can be restored to normal, so there will be the phenomenon of high and low blood pressure. 3. Not taking antihypertensive drugs regularly: If hypertensive patients do not take antihypertensive drugs in strict accordance with the doctor’s instructions, and take them from time to time and stop using them, then there will be the situation of blood pressure fluctuating between high and low. When the blood pressure is high or low but within the normal range, there is no need to worry too much; if the blood pressure is higher than 140/90mmHg or lower than 90/60mmHg, it is recommended to consult a doctor in time to clarify the specific cause of the disease and comply with the doctor’s instructions to standardize the treatment, so as not to aggravate the condition.