Low blood pressure may be due to physiological factors, such as postural hypotension, etc. It may also be due to pathological factors such as hypothyroidism, severe aortic valve stenosis and congestive heart failure. 1. Physiological factors: commonly found in postural hypotension, which is a small decrease in blood pressure that occurs mainly after changing from a lying position to a standing position, and is commonly found in middle-aged and elderly people. Secondly, during pregnancy, due to the rapid expansion of the blood system, resulting in a drop in blood pressure, after giving birth to a child will return to the normal level before pregnancy. And after eating, a large amount of blood in the body may be allocated to the gastrointestinal tract to help digestion, thus reducing the blood supply to the cardiovascular and cerebrovascular vessels causing low blood pressure; in addition to this, under the influence of emotional excitement, lack of water and other factors, can also cause low blood pressure. 2. Pathological factors: commonly found in multiple sclerosis, myasthenia gravis, hypopituitarism, hypothyroidism, severe stenosis of aortic valve, congestive heart failure, hypertrophic obstructive cardiomyopathy, malignant tumors and other diseases. In addition to this, the application of sedative and hypnotic drugs and vasodilator drugs may lead to a decrease in the pressure on the side walls of blood vessels during blood flow, thus causing symptoms of low blood pressure. When the above symptoms appear, it is recommended to go to the hospital in time for early and regular treatment.