Clinically, infusion is generally required in the following four cases: 1. When poor digestive function prevents oral administration. Such as when suffering from certain gastrointestinal diseases that require fasting and when digestive function is affected; when unconsciousness prevents oral administration. 2.When topical application is not effective. Such as skin diseases preferred topical drugs, but if the topical drugs can not achieve the corresponding effect need to infusion. 3.Serious emergencies that cannot be relieved by oral medication. Acute diseases, such as acute pneumonia, shock, etc., the effect of drugs is not obvious, need to infusion. 4.When the drug may harm the tissues and blood vessels. Certain chemotherapy drugs for the treatment of tumors, if taken orally directly, may harm blood vessels and even cause tissue necrosis, so infusion can be used at this time.