Hypertension is a very serious cardiovascular disease, and is also an important cause of many other cardiovascular diseases. Patients with hypertension need to adhere to long-term medication to control blood pressure, but there are some cases where hypertension can suddenly become hypotension, common causes include the following: 1. Overdose of medication. There are some patients taking antihypertensive drugs, there is no certain rule, suddenly increase the amount of medication or after the use of less appropriate antihypertensive drugs, there is a possibility of low blood pressure. If this is the case, take the medication regularly to avoid hypotension, and to avoid excessive fluctuations in blood pressure. 2, sudden myocardial ischemia. Coronary artery disease may lead to a decrease in the systolic and diastolic functions of the heart, which can lead to a drop in blood pressure. 3, patients with long-term hypertension and coronary artery disease may also develop hypotension after the development of heart failure, which is caused by a decrease in the contractility of the heart muscle. 4, rapid arrhythmias, if there is a disturbance in hemodynamics, will also appear hypotension. 5, the development of a drop in blood volume or other causes of severe Hypotension, if there is a disorder of consciousness, clinically called shock, are at risk. Therefore, once hypertension becomes hypotension, it is important to actively search for the cause and to actively treat it to prevent more serious conditions.