Mirtazapine-induced serotonin syndrome

Clin Neuropharmacol. 2003 Mar-Apr;26(2):54-7. doi: 10.1097/00002826-200303000-00002.


An 85-year-old woman developed sudden confusion and dysarthria progressing to mutism, orobuccal dyskinesias, generalized tremors worse with activity, ataxia, and rigidity with cog wheeling without high-grade fevers or dysautonomia. These findings were related temporally to the institution of mirtazapine as monotherapy for a major depressive illness with superimposed anxiety disorder. Withdrawal of the agent resulted in early notable clinical resolution with only residual hypertonia after 2 weeks. This is a rare report of serotonin syndrome induced by mirtazapine monotherapy. The hypothesized pathophysiologic mechanism in this case is overstimulation of serotonin (5-hydroxytryptamine or 5-HT) type 1A receptors (5-HT(1A)) in the brainstem and spinal cord in an individual with risk factors for hyperserotoninemia resulting from reduced, acquired endogenous serotonin metabolism.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Aged, 80 and over
  • Female
  • Humans
  • Mianserin / adverse effects*
  • Mianserin / analogs & derivatives
  • Mirtazapine
  • Serotonin Syndrome / chemically induced*
  • Serotonin Syndrome / diagnosis


  • Mianserin
  • Mirtazapine