Physiological saline and sterile saline are the same substance, but sterile saline is kept under aseptic conditions, and the expiration date of sterile saline is relatively short after opening. Both saline and sterile saline are sodium chloride solutions with a concentration of 0.9%. Stored under aseptic conditions it is called sterile saline and can be used clinically as a solvent for injections and also for skin disinfection. Sterile saline has a certain shelf life after opening, if it is not kept under sterile conditions and exceeds the expiration date of 2 hours, it can only be called saline and can no longer be used as an injection solvent. It is recommended to use the above medications in a reasonable manner. If they are opened for more than 24 hours, they are prone to harboring bacteria, etc. and are not recommended for use.