How long to change the plaster paste depends on the type of plaster, ordinary plaster is generally used for 12 hours. Ordinary plasters are divided into 12 hours, 24 hours, 72 hours three kinds of preparations, that is, the maximum use of 72 hours, it is recommended to change once in 12-24 hours. If the drug has special instructions or the doctor has medical advice, follow the medical advice to correctly choose the use and replacement of the plasters so as not to affect the efficacy of the drug and expect the plasters to achieve the best therapeutic effect. At present, most of the plasters applied in hospitals are used for relieving pain caused by bruises and treating frozen shoulder. There are more types of plasters, such as those for bruises or for pain relief alone, and the action time is generally 12-72 hours. Some creams have a longer duration of action, lasting about a week. Therefore, the replacement time of plasters should be based on the preparation of the plaster, the instructions of the drug and the doctor’s prescription.