Dexamethasone is a type of steroid medication. It is used in the treatment of rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive lung disease, croup, brain swelling, and along with antibiotics in tuberculosis, among others. In adrenocortical insufficiency it should be used together with a medication that has greater mineralocorticoid effects such as fludrocortisone. In preterm labor it may be used to improve outcomes in the baby. It may be taken by mouth, as an injection into a muscle, or intravenously. The effects of dexamethasone are frequently seen within a day and last for about three days.