The prognosis is best when identified early and treated aggressively. In these cases NMS is not usually fatal. In earlier studies the mortality rates from NMS ranged from 20%–38%, but by 2009 mortality rates were reported to have fallen below 10% over the previous two decades due to early recognition and improved management. Re-introduction to the drug that originally caused NMS to develop may also trigger a recurrence, although in most cases it does not.
