The main cause is stopping steroid medications too quickly after long-term use. When you take glucocorticoids like prednisone, hydrocortisone, or dexamethasone for several weeks, your brain stops signaling your adrenal glands. The hypothalamic-pituitary-adrenal axis, or HPA axis, shuts down because it senses enough steroid in your blood. Taking more than 20 milligrams of prednisone daily for over 3 weeks usually suppresses the HPA axis. Lower doses taken for many months can also cause suppression.
Risk factors include high steroid doses, long treatment duration, and previous episodes of withdrawal. People who take evening doses face higher risk because cortisol normally peaks in the morning. Taking steroids for asthma, autoimmune diseases, organ transplants, or cancer treatment increases exposure. Stress from surgery, infection, or injury can trigger adrenal crisis in people tapering steroids. Their bodies need extra cortisol during stress but cannot produce it. Age does not prevent this condition, and it affects both adults and children on chronic steroid therapy.