There are many reasons for the sudden decrease in blood pressure, as follows: 1, pathological reasons: for example, the patient has an acute myocardial infarction, especially the left main lesion, this situation is a sharp drop in the heart’s blood ejection, the patient will soon appear hypotension, and even the performance of shock; another situation is trauma, after trauma, a large amount of blood loss, the body circulation blood volume is insufficient, this situation will also suddenly drop in blood pressure; the most common situation is to take antihypertensive drugs, such as overdose of antihypertensive drugs, especially the short-acting class of drugs to take effect more quickly, this situation will also suddenly drop in blood pressure; 2, physiological reasons: postural hypotension, also known as postural hypotension. The most common situation is to take antihypertensive drugs, such as taking an overdose of antihypertensive drugs, especially short-acting class of drugs with a faster onset of action, this situation will also be a sudden drop in blood pressure; 2, physiological causes: postural hypotension, that is, the patient from the prone position to the upright position, the blood pressure suddenly dropped, this situation can also occur in the normal population; temperature rises a lot of sweating can also make vasodilation lead to blood pressure This can also happen in normal people. Therefore, there are many causes of sudden decrease in blood pressure. When you encounter a sudden decrease in blood pressure, you must observe whether there is chest tightness, panic, shortness of breath, black stool and other conditions, and if necessary, you should go to the hospital.