Morphine belongs to the opioid class of painkillers and will be used for more severe pain, such as patients with moderate or severe cancer pain. Some patients may experience adverse reactions after morphine injection, such as nausea, vomiting, acid reflux, etc. Some patients may experience skin rash and generalized itching, and fever is also a relatively common side effect. If patients use a large amount of morphine, it is likely that they will also experience respiratory depression causing deep and rapid breathing or even respiratory failure. Long-term use of morphine can lead to drug dependence and addiction, causing patients to use small doses of morphine to relieve pain, and they need to give morphine regularly every day.