Shizi li zhongwan is a traditional Chinese medicine formula composed of shizi, dangshen, atractylodes macrocephala (fried), dry ginger, licorice, with the effect of warming and strengthening the spleen, clinically used for the spleen and stomach cold, cold pain in the stomach and abdomen, vomiting and diarrhea, hands and feet do not have warmth and other diseases. How long is its expiration date? No matter what kind of drug, there is a half-life. The half-life of a drug generally refers to the time it takes for the highest concentration of the drug in the plasma to decrease by half. For example, if a drug has a half-life of 6 hours, then after 6 hours the blood concentration of the drug will be half of its maximum value. The half-life of a drug reflects the rate of elimination (excretion, biotransformation and storage, etc.) of the drug in the body, indicating the relationship between the time the drug is in the body and the blood concentration, which is the main basis for deciding the dose and frequency of drug administration. The half-life of each drug is different; even the same drug for different individuals its half-life is not exactly the same; adults and children, the elderly, pregnant women, healthy people and patients, drug half-life will be different. The half-life of a drug is usually an average. In patients with hepatic and renal insufficiency, the elimination of drugs is slow, and the half-life will be relatively prolonged. Special attention must be paid to the risk of toxicity if the drug is administered as prescribed. According to the length of the half-life of the drug, can ensure that the blood concentration of the drug to maintain in the most appropriate therapeutic concentration without causing toxic reactions. In addition, the way in which a drug is stored and the location and environment in which it is stored are also affected by the production of the drug. If not properly stored, the drug will be oxidized by oxygen in the air or ultraviolet rays of the sun, or react with certain chemical components in the environment or itself, resulting in the inactivation of the drug's medicinally active substances. Therefore, every medicine has its expiration date, and Radix Rehmanniae Pill is no exception. Its expiration date is 2 years. Therefore, if you need to use this drug, you need to use it according to the expiration date indicated in the manual, so as not to achieve the desired effect of the drug, which affects the condition.