The dosage of alum is 0.6~1.5g for internal use and appropriate amount for external use, the basic effects are: external detoxification and insecticide, dampness and itching; internal use to stop bleeding and diarrhea, expectorate wind and phlegm. Alum can be used externally to treat skin disorders such as sores, itchy skin and so on. Internal use can be astringent to stop bleeding (with astringent drugs to treat bleeding disorders), astringent to stop diarrhea (through the enhancement of intestinal astringency to relieve diarrhea), for blood in the stool, diarrhea for a long time, etc.; cold in nature, can be cleared of heat to resolve phlegm, suitable for phlegm obsessed with the heart and orifices, confusion, epilepsy, and madness, etc.. The Chinese Pharmacopoeia stipulates that the dosage of alum for internal use is 0.6~1.5g; for external use, the appropriate amount of powdered compresses or water to wash the affected area, the specific dosage needs to be decided by the doctor according to the individual’s physical condition, the severity of the disease and other factors. The adverse reactions and contraindications of alum are not clear. If there is any discomfort, please go to the hospital, under the guidance of the doctor to use medication, do not blindly self-medication.