Medrol etc. (methylprednisolone) is an adrenal corticosteroid that has potent anti-inflammatory properties.
Corticosteroids are synthetic drugs that closely resemble cortisol, a hormone that is naturally produced by the adrenal glands. Corticosteroids work by decreasing inflammation and reducing the activity of the immune system. They lessen swelling, redness, itching, and allergic reactions. They are often used as part of the treatment for a number of different diseases, such as severe allergies or skin problems, asthma, or arthritis. Methylprednisolone is stronger than prednisone, another common steroid medication. Other corticosteroids include prednisolone (a derivative of prednisone that has been chemically changed for easy passage through the liver); hydrocortisone (weaker in strength than prednisone); and dexamethasone (which is extremely potent and is only used in unusual circumstances).