In clinical outpatient and ward work, doctors often ask patients whether they have underlying diseases, which is actually a relatively broad concept and category, usually referring to chronic diseases, such as hypertension, hyperlipidemia, diabetes and other “three high” diseases, as well as diseases that have occurred in the past and require long-term drug treatment, including coronary heart disease, cerebrovascular disease diseases, including coronary heart disease, cerebrovascular disease, etc. In addition, tumor diseases, chronic kidney diseases and liver diseases can also be considered as basic diseases. The consultation of the underlying disease helps the doctor to determine the overall health status of the patient, and in the process of treating the disease, the doctor also takes into account the patient’s underlying condition, whether there is any damage to liver and kidney function, or whether there is any conflict with other diseases in the process of medication, and in the process of medication guidance, try to choose drugs that reduce damage to liver and kidney function. Therefore, in the course of daily outpatient visits, it is important to be aware of the underlying disease and to take the initiative to inform the doctor of the disease that has occurred or the disease that requires continuous medication, so as to help the doctor judge the condition and choose a reasonable treatment with minimal side effects.