It is generally safer to take dexamethasone for about half a month as prescribed by the doctor, but if the dose is too large, it is not safe and can easily cause Cushing’s syndrome, diabetes and other diseases. Dexamethasone belongs to the adrenocorticotropic hormone drug, if the patient strictly follow the doctor’s instructions to take the appropriate amount of half a month or so, in general, is relatively safe. Taking more than 1 month belongs to long-term use, patients need to follow up regularly blood sugar, eye examination, serum electrolytes and other items. However, if a patient takes too much dexamethasone, it is not safe and can adversely affect their health. For example, for the treatment of autoimmune hemolytic anemia, the recommended dose is 7.5 mg per day, while 40 mg per day is commonly used for the treatment of multiple myeloma, and the dose should be appropriately lowered under the guidance of a physician for patients who are older or have co-infections. Prolonged use of dexamethasone tablets or taking too high a dose is likely to cause skin thinning and full moon face and other symptoms of Cushing’s syndrome, or diabetes, osteoporosis, peptic ulcer and other diseases. In short, patients must take dexamethasone under the guidance of a doctor, do not self-medication, in order to avoid adverse consequences.