If you have a dry cough for a month, most of the time you have applied cough medicine in the early stage of the cold. Cold is an external heat or wind evil, which is an inflammation in the body. In the early stage, it should help the body to disperse the virus or pathogen as much as possible, so at the beginning, it is not recommended to use some astringent and acidic drugs, such as some tablets and cough syrup, or some acidic ones, whether they are drugs or food, which will lead to the unfavorable publication of the disease when you have a cold, and it will not be easy to clear the body at a later stage, so the body will continue to clear the body. This will cause a recurrent cough. At this time, you should use some phlegm medicine to help the dirt inside the airway or inside the lungs to get out as quickly as possible. Sometimes it is also because the heat is not cleared enough at the beginning of the cold, which leads to some residual heat later on. If this is the case, if the dry cough has been going on for a month, you should use some medicine to nourish Yin and clear the lungs to help clear the remaining ones.