Systemic glucocorticoid therapy is used worldwide by one to three percent of the general population and 0.5-1.8% on long-term oral glucocorticoid use. It is widely used in conditions such as inflammation, autoimmune diseases, and cancer to inhibit inflammatory responses. One of the possible undesirable side effects of exogenous corticosteroid treatment is adrenal suppression upon discontinuation of the medication and adrenal insufficiency after utilizing the supraphysiologic doses for more than one month. To prevent patients from the unwanted signs and symptoms of adrenal insufficiency, including fatigue, gastrointestinal upset, anorexia/weight loss, etc., better management of the quantity and frequency of exogenous corticosteroid use, as well as better education before starting its use, is needed. For patients actively on exogenous corticosteroids, a close follow-up must be in place to avoid adrenal suppression after the eventual discontinuation of their use. This review article summarizes the important studies to date on this subject, especially oral glucocorticoid use, and analyzes risks such as dose, duration of exposure, and comorbidities of adrenal insufficiency associated with oral glucocorticoid use. We comprehensively include information on those with primary adrenal insufficiency and pediatric patients, hoping to provide better insight and clinical reference.