Betamethasone is a steroid medication. It is used for a number of diseases including rheumatic disorders such as rheumatoid arthritis and systemic lupus erythematosus, skin diseases such as dermatitis and psoriasis, allergic conditions such as asthma and angioedema, preterm labor to speed the development of the baby's lungs, Crohn's disease, cancers such as leukemia, and along with fludrocortisone for adrenocortical insufficiency, among others. It can be taken by mouth, injected into a muscle, or applied to the skin, typically in cream, lotion, or liquid forms.