Dexamethasone, a corticosteroid, is similar to a natural hormone produced by your adrenal glands. It often is used to replace this chemical when your body does not make enough of it. It relieves inflammation (swelling, heat, redness, and pain) and is used to treat certain forms of arthritis; skin, blood, kidney, eye, thyroid, and intestinal disorders (e.g., colitis); severe allergies; and asthma. Dexamethasone is also used to treat certain types of cancer. Dexamethasone comes as a tablet and a solution to take by mouth. Your doctor will prescribe a dosing schedule that is best for you. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take dexamethasone exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor. Do not stop taking dexamethasone without talking to your doctor. Stopping the drug abruptly can cause loss of appetite, upset stomach, vomiting, drowsiness, confusion, headache, fever, joint and muscle pain, peeling skin, and weight loss. If you take large doses for a long time, your doctor probably will decrease your dose gradually to allow your body to adjust before stopping the drug completely.