Dexamethasone for Treatment of Radiation-related Fatigue in Patients Receiving RT for Head-neck and Lung Cancer

Inclusion Criteria: * confirmation of head \& neck cancer (stage I-IV) or non-small cell lung cancer (stage II \& III) * Undergoing treatment with either radiation alone or in combination with chemotherapy * Normal cognition and willingness to complete fatigue and quality of life forms, patient observation form, and pill diary Exclusion Criteria: * Hypersensitivity to dexamethasone or corticosteroids or Equal sugar substitute * Corticosteroid within the past 30 days prior to study enrollment for greater than one week duration * Planned Stereotactic Body Radiation Therapy (SBRT) * Active psychosis * Current pregnancy * Active peptic ulcer disease or evidence of gastrointestinal bleed * Current active tuberculosis or systemic fungal infection * Previous diagnosis of diabetes mellitus * Acute febrile illness * Known human immunodeficiency virus or acquired immunodeficiency syndrome * Major surgery within two weeks of study enrollment of which the patient has not recovered * Psychostimulant use in the past 30 days prior to registration * History of phenylketonuria (PKU)