A large class of highly useful
drugs similar to the human body's natural corticosteroid
hormones used to treat many types of
inflammation. They are also sometimes used to suppress the
immune system (as is standard treatment following a
transplant). Treatment for
asthma and
rheumatism has improved vastly since the introduction of corticosteroids.
Bad side effects include hypertension, fluid retention, and possibly even diabetes mellitus (with long-term treatment in high doses).
Since these drugs mimic the effects of hormones, the body's own production of them may cease. Sudden withdrawal of corticosteroid drugs after long-term treatment can therefore cause the symptoms of adrenal failure.
(Summarized from AMA literature)