Depo-Medrol suspension is used for: Treating certain conditions associated with decreased adrenal gland function. It is also used to treat severe inflammation caused by certain conditions, including severe asthma, severe allergies, rheumatoid arthritis, ulcerative colitis, certain blood disorders, lupus, multiple sclerosis, and certain eye and skin conditions. It may also be used for other conditions as determined by your doctor. Depo-Medrol suspension is a corticosteroid. It works by modifying the body's immune response and decreasing inflammation.