Abstract
Steroid-induced psychosis is a known adverse effect of treatment with corticosteroids. On average, the time of onset is several days after exposure to the steroid. A 91-year-old man presented with left buttock pain with radicular features and was found to have severe left lateral recess spinal canal stenosis on MRI. He was started on a prednisone taper and developed steroid-induced psychosis one day later. He was treated with a short course of antipsychotic medication. This case discusses the unusually rapid onset of steroid-induced psychosis at a dose of prednisone that does not commonly cause this adverse effect. It emphasizes important considerations when starting steroids in patients with advanced age and comorbidities that may impact the metabolism of steroids.