Selective Serotonin Reuptake Inhibitor Toxicity Workup

Updated: Apr 24, 2018
  • Author: Tracy A Cushing, MD, MPH, FACEP, FAWM; Chief Editor: Michael A Miller, MD  more...
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Approach Considerations

Diagnosis of serotonin toxicity begins with a detailed history of the patient's medications, of changes to regimen, and of possible overdose; queries into the availability of serotonergic drugs; and a careful physical examination. Laboratory tests used in the diagnosis of serotonin toxicity may include the following:

  • Serum and urine toxicology screen - Opiates/opioids (meperidine), salicylates, acetaminophen, TCAs, amphetamines, phencyclidine (detection of dextromethorphan by cross-reactivity), and cocaine

  • Total creatine phosphokinase

  • Urine myoglobin

  • Basic electrolytes, including calcium, magnesium, and phosphorus levels, as well as lactate and ketone levels - to evaluate for metabolic acidosis

  • Blood urea nitrogen (BUN) and creatinine levels

  • Serum pH level

  • Liver function tests

  • Complete blood count and blood cultures if febrile

  • Prothrombin time/activated partial thromboplastin time in severe cases; disseminated intravascular coagulation panels, if necessary

  • Pregnancy testing, if indicated

  • Electrocardiography - To determine rhythm, morphology, and intervals, particularly in suspected co-ingestions

Imaging studies

Imaging studies include chest radiograph after intubation or in any patient with hypoxia or aspiration. Head computed tomography (CT) scanning can be conducted in any patient with suspected trauma, new-onset seizures, or hypertension and localizing neurologic findings


Intubation should be considered in any unstable patient or any patient with altered mental status who cannot protect his or her airway. Lumbar puncture is indicated in any patient with fever and altered mental status.