This report describes a rare but life-threatening case of a suicide attempt initially considered as intentional overdose at the emergency department. Persistent altered mental status, despite normal toxicology investigations, led the attending team to order a head computed tomography scan, which revealed a bilateral penetrating nail gun injury with a right temporal hematoma for which a decompressive craniectomy was performed. Although voluntary intoxication is the most frequent form of suicide attempt, emergency physicians must be alert and maintain a broad differential diagnosis. Although rare, penetrating head injuries have increased in recent decades. As neurological symptoms can be minimal and penetration wounds small, this type of injury could potentially be overlooked.