Mannitol plus dexamethasone drip the next morning to wake up dizziness is most likely due to the dehydration effect is too strong and caused by the symptoms of upright hypotension and drug non-response related. Mannitol is widely used in clinical treatment due to its high dehydration efficiency, economy and low side effects, and is commonly used in the treatment of increased intracranial pressure, lowering intraocular pressure, decongestion and diuresis, and bowel preparation. By virtue of its high osmotic concentration and thus dehydration, but too much too fast easily lead to electrolyte disorders, dizziness, hypotension and other side effects. Dexamethasone, on the other hand, as a hormone, in addition to its anti-inflammatory effect, also has an auxiliary dehydrating effect and improves the efficiency of dehydration. As a result, upright hypotension and dizziness can occur. Discomfort symptoms occur during the use of medication, it is recommended to consult the attending physician in a timely manner, combined with a comprehensive analysis of the condition to deal with.