They usually control the disease rather than cure it. These drugs are modifications of natural hormones produced by the adrenal glands. While the corticosteroids can be very effective, they can cause adverse effects. These adverse effects are a particular problem when the drugs are taken for a long time. They are more common at higher doses.
Corticosteroids can cause high blood pressure, thinning of the bones and diabetes.
Supplementary doses may be needed during an acute illness. Treatment aims to achieve the best effect with the lowest dose. This explains why people are sometimes told to reduce their dose of corticosteroids even though they are feeling better. The risks and benefits of treatment vary depending on the disease. You should ask your doctor to explain this balance.