Hallucinogen Toxicity Workup

Updated: Jan 29, 2021
  • Author: Joseph L D'Orazio, MD, FAAEM, FACMT; Chief Editor: Sage W Wiener, MD  more...
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Laboratory Studies

Testing directed at confirming exposure to a hallucinogenic substance is rarely useful. Treatment is symptom guided and results of confirmatory testing are not rapidly available.

The urine drug screen (UDS) may be misleading when used to diagnose the cause of presenting clinical features. The UDS is limited and often does not contain a screen for common hallucinogens. In addition, false-positive and false-negative results are common with the typical UDS immunoassay (eg, diphenhydramine, dextromethorphan, and venlafaxine have been reported to cause a false-positive phencyclidine screen). [32, 33] Finally, even a true-positive UDS result does not always identify the cause of a patient's current presentation; for example, the UDS could be positive for phencyclidine because the patient took it 3 days ago.

Laboratory tests such as basic metabolic profiles, blood gases, hormonal concentrations (thyroid-stimulating hormone, cortisol), and creatine kinase can be used to identify complications from hallucinogens and exclude alternative causes of altered mental status (eg, acid-base disturbances, metabolic and endocrine pathology, electrolyte abnormalities, rhabdomyolysis, renal failure, or stroke).

When exposure confirmation is necessary (ie, forensic cases, research purposes) expanded drug testing can be performed using specialized immunoassays, liquid chromatography and mass spectrometry, or a variety of other methods which are available through specialized reference laboratories.


Imaging Studies

Imaging is rarely useful in evaluating the effects of hallucinogen exposure. However, advanced imaging, including computed tomography or magnetic resonance imaging of the brain, can be useful in identifying complications and clinical disorders often associated with recreational hallucinogen use, including trauma, infection, hyperthermia, and hypertensive crisis.