Background: Water intoxication can induce life-threatening hypotonic encephalopathy. If undiagnosed or inadequately treated, cerebral edema can progress to brain death due to uncal herniation. We report herein a patient with refractory depression who was found unresponsive because of clandestine self-induced water intoxication. Emergent infusion of intravenous hypertonic (3%) saline rapidly restored consciousness, leading to a full recovery without complications.