To make sure dexamethasone is safe for you, tell your doctor if you have: 1  tuberculosis; 2  cirrhosis or other liver disease; 3  kidney disease; 4  a thyroid disorder; 5  a history of malaria; 6  osteoporosis; 7  a muscle disorder such as myasthenia gravis; 8  glaucoma or cataracts; 9  herpes infection of the eyes; 10  stomach ulcers, ulcerative colitis, or diverticulitis; 11  dep