Participants will be assigned to receive one of the two treatments through the mouth. The study involves monitoring the intensity of mouth pain during and after the use of these medications. This process will take place during radiotherapy, which is a common treatment for cancer that uses radiation to target cells, and for several weeks following the completion of that treatment.

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.

The purpose of the study is to see if Apremilast can help patients with severe RAS by reducing or eliminating their mouth ulcers over a period of time. Participants in the study will be randomly assigned to receive either Apremilast or a placebo. The study will last for several weeks, during which time the participants will take the medication and have regular check-ups to monitor their progress. The main goal is to see if the ulcers are completely gone at specific points during the study.

Throughout the study, participants will be closely monitored by healthcare professionals to ensure their safety and to assess the effectiveness of the treatment. The study aims to provide valuable information on whether Apremilast can be a beneficial treatment option for those suffering from severe forms of RAS, offering hope for better management of this painful condition.

The purpose of the study is to evaluate how effective dexpanthenol solution is in reducing the severity of mouth inflammation compared to a placebo mouth rinse. During the study, participants will use either the dexpanthenol mouth rinse or placebo while receiving their regular radiation therapy. The treatment period will last about 9 weeks.

Throughout the study, healthcare providers will monitor various aspects of participants’ health, including mouth discomfort, ability to taste food, breathing through the nose, swallowing ability, and overall quality of life. They will also track any side effects that may occur from the mouth rinse or radiation therapy. The total duration of the study is expected to be approximately three years.