Melatonin for Prevention of Radiation Induced Oral Mucositis

Inclusion Criteria: * Patients who are going to receive radiotherapy as a treatment of head and neck cancer either as postoperative (adjuvant) therapy or definitive therapy. * Patients whose radiotherapy treatment planned dose is between 60-70 Gy. * Patients who had received chemotherapy prior to radiotherapy or are going to receive chemotherapy in concomitant to radiotherapy. Exclusion Criteria: * Patients under Anticoagulants such as warfarin, heparin, or aspirin. * Patients under Fluvoxamine (Luvox) and Nifedipine medications. * Patients whose radiotherapy treatment planned dose is lower than 60 Gy. * Pregnant and lactating women. * Patients suffering from any uncontrolled systemic diseases (such as diabetes, cardiovascular, liver disorder, renal dysfunction) * Patients with findings of any physical or mental abnormality which would interfere with or be affected by the study procedure.