This study aims to compare the effectiveness of two ways of giving a medication to manage pain caused by Oral mucositis. This condition involves painful inflammation and sores in the mouth and throat, which often occurs as a side effect of treatments like chemotherapy or radiotherapy. The study focuses on patients undergoing a hematopoietic stem cell transplantation, a procedure used to replace damaged bone marrow with healthy stem cells.

One group will receive esketamine hydrochloride in the form of a mouthwash, which is swallowed or used to rinse the mouth. The other group will receive esketamine through an intravenous infusion, which means the medicine is delivered directly into a vein. By comparing these two methods, researchers want to see if the mouthwash can provide similar pain relief to the liquid delivered through a vein.

During the study, participants will have their pain levels monitored to see how well each method works. Information will also be collected regarding side effects, the ability to eat or drink, and the amount of other pain medications needed during the treatment period. The researchers will also check the levels of the medication in the blood to understand how the body processes it through different methods.