In people who take large doses of corticosteroids, such as prednisone, the function of the adrenal glands can become suppressed. This suppression occurs because large doses of corticosteroids signal the hypothalamus and pituitary gland to stop producing the hormones that normally stimulate adrenal function.
If the person abruptly stops taking corticosteroids, the body cannot restore adrenal function quickly enough, and temporary adrenal insufficiency (a type of secondary adrenal insufficiency) results. Also, when stress occurs, the body is not able to stimulate production of the additional corticosteroids that are needed.
Therefore, doctors never stop the use of corticosteroids abruptly if people have been taking them for more than 2 or 3 weeks. Instead, doctors gradually reduce (taper) the dose over weeks and sometimes months.
Also, the dose may need to be increased in people who become ill or otherwise severely stressed while taking corticosteroids. Corticosteroid use may need to be resumed in people who become ill or otherwise severely stressed within weeks of having the corticosteroid tapered and stopped.