Lumbar spinal stenosis (LSS) is a common spinal disease in the elderly. The cardinal symptom of LSS is neurogenic claudication, but not all patients present with such typical symptom. The clinical symptoms are often confused with symptoms of peripheral neuropathy, musculo-skeletal disease and other medical conditions in elderly patients. In particular, LSS presenting with rapid progression of leg weakness must be distinguished from other combined diseases. We report a case of rapid progressive leg weakness in a patient with LSS and iatrogenic adrenal insufficiency that was induced by obscure health supplement.