Using a Steroid Mouthwash to Prevent Mouth Sores During Chemotherapy

The goal of this clinical trial is to learn if a steroid mouthwash (dexamethasone) can prevent mouth sores caused by chemotherapy in adults with cancer. The main questions it aims to answer are: Does using dexamethasone mouthwash before and during chemotherapy lower the chance of getting moderate to severe mouth sores? Can this approach reduce pain and improve comfort during chemotherapy? Researchers will compare patients using the mouthwash to a historical group of patients who received similar chemotherapy but did not use the mouthwash, to see if the mouthwash helps prevent mouth sores. Participants will: Use a steroid mouthwash (4 times daily) for up to 8 weeks during chemotherapy Complete a short weekly survey about mouth discomfort during infusion visits

Inclusion criteria: * ≥18 years old * Confirmed cancer diagnosis * Scheduled to receive or receiving chemotherapy known to be associated with oral mucositis (e.g., anthracyclines and taxanes) * Ability to provide informed consent * Ability to comply with study procedures Exclusion criteria: * Current tobacco usage or usage within the past 6 weeks. * HIV/AIDS * Gastrointestinal disorder (such as Crohn's disease, ulcerative colitis, or celiac disease) * History of cold sores (herpes simplex virus) * Herpes zoster (oral shingles) within the past 6 weeks * Active oral infections at the time of enrollment (e.g., candidiasis) * Known sensitivity or allergy to dexamethasone * Inability to self-administer or tolerate mouthwash protocol * Concurrent enrollment in conflicting clinical trials * Existing oral ulcers or oral mucositis at enrollment * Pregnant * Uncontrolled diabetes mellitus as defined by HbA1c unknown or \>8% in the past 3 months despite adequate therapy