Glucocorticoids are the most commonly prescribed anti-inflammatory/immunosuppressant medications worldwide. This article highlights the risk of clinically significant and sometimes severe psychological, cognitive, and behavioral disturbances that may be associated with glucocorticoid use, as well as ways to prevent and treat these disturbances. An illustrative case vignette is presented describing a patient's experience of cycles of manic-like behavior and depression while on high-dosage prednisone, with long-term cognitive disorganization, vulnerability to stress, and personality changes. Severe neuropsychiatric consequences (including suicide, suicide attempt, psychosis, mania, depression, panic disorder, and delirium, confusion, or disorientation) have been reported to occur in 15.7 per 100 person-years at risk for all glucocorticoid courses, and 22.2 per 100 person-years at risk for first courses. The majority of patients experience less severe but distressing and possibly persistent changes in mood, cognition, memory, or behavior during glucocorticoid treatment or withdrawal. Although prediction of such effects is difficult, risks vary with age, gender, dosage, prior psychiatric history, and several biological markers. Key mechanisms thought to underlie these risk factors are briefly described. Recommendations are given for identifying individual risk factors and for monitoring and managing adverse neuropsychiatric effects of glucocorticoids.