Corticosteroids mimic the effects of hormones your body produces naturally in your adrenal glands, which sit on top of your kidneys. When prescribed in doses that exceed your body's usual levels, corticosteroids suppress inflammation.This can reduce the signs and symptoms of inflammatory conditions, such as arthritis and asthma.hen prescribed in doses that exceed your body's usual levels, corticosteroids suppress inflammation. This can reduce the signs and symptoms of inflammatory conditions, such as arthritis and asthma.