SNRI Toxicity


  • Inhibits reuptake of serotonin, norepinephrine and small effect on dopamine
  • Adverse effects similar to SSRIs, but more dangerous
  • Venlafaxine (Effexor)
    • Can produce mild to moderate hypertension
  • Duloxetine (Cymbalta)
    • Nausea, vomiting, dizziness

Clinical Features

  • Sympathomimetic: tachycardia, hypertension, diaphoresis, tremor, mydriasis
    • Secondary to inhibition of norepinephrine reuptake
  • Sedation
  • Seizures
  • Rhabdomyolysis
    • 25% occur without seizures
  • ECG
    • Most common abnormality: sinus tachycardia
    • May see QRS widening, QT prolongation and ventricular dysrhythmias
  • Serotonin syndrome



  • Supportive Care
    • Cardiac monitoring
    • Benzodiapazines for seizures
    • GI Decontamination
      • A single dose of activated charcoal, 1 g/kg (typical adult dose is 50 g), may be given to a patient who presents within one to two hours of ingestion.
      • AC should not be given to patients at risk for aspiration


  • Admit all symptomatic patients to a monitored bed
  • Monitor for 6 hours, longer for extended-release preparations

See Also


  • Mills K. Atypical Antidepressants, Serotonin Reuptake Inhibitors, and Serotonin Syndrome In: Tintinalli's Emergency Medicine. 7th ed. McGraw Hill. 2011:1198-2002