Patients who feel dizzy while standing up after sitting for a long time should consider the following factors: First, consider upright hypotension, also known as postural hypotension, which is a clinical manifestation of abnormal blood pressure regulation and is particularly common in the elderly population, or patients who experience significant clinical symptoms such as dizziness, blackness and fainting discomfort after sitting up or suddenly standing up, usually with non-pharmacological treatment as a priority. Second, if the patient has hypovolemia caused by various factors, such as when the patient has heat stroke in summer, or if the patient has severe dehydration resulting in decreased blood volume, this clinical manifestation will also occur. Third, the adverse reactions and side effects of taking a large amount of certain drugs for a long time, such as long-term use of diuretics or antidepressants, vasodilators, will also have the symptoms of dizziness from sitting to standing up. Fourth, if the patient has chronic cardiac insufficiency, chronic heart rhythm failure, or severe anemia, he or she will also have the above-mentioned condition due to the weakened regulation of internal environmental homeostasis.