Dexamethasone prescribed for: Dexamethasone is used for reducing inflammation in many conditions. Some examples include rheumatoid arthritis, systemic lupus, acute gouty arthritis, psoriatic arthritis, ulcerative colitis, and Crohn's disease. Severe allergic conditions that fail to respond to other treatments also may respond to dexamethasone. Examples include bronchial asthma, allergic rhinitis, drug-induced dermatitis, and contact and atopic dermatitis. Chronic skin conditions treated with dexamethasone include dermatitis herpetiformis, pemphigus, severe psoriasis and severe seborrheic dermatitis. Chronic allergic and inflammatory conditions of the uvea, iris, conjunctiva and optic nerves of the eyes also are treated with dexamethasone.