LSD Toxicity Workup

Updated: Jan 26, 2023
  • Author: Paul P Rega, MD, FACEP; Chief Editor: Stephen L Thornton, MD  more...
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Approach Considerations

Lysergic acid diethylamide (LSD) toxicity is diagnosed primarily by way of history and physical examination. Most routine drug screens do not detect LSD. In the urine, it is excreted primarily as 2-oxy-lysergic acid diethylamide, which is pharmacologically inactive. Only small amounts of LSD are excreted unchanged in the urine. [40]

The drug can be detected by radioimmunoassay; levels from 1.5-5.5 ng/mL may be found within 24 hours after the patient has taken a 300-mcg dose of LSD. However, high-performance liquid chromatography or gas chromatography is required for confirmation. LSD levels in the urine do not correlate with severity of symptoms. [41, 42]

Although urine tests may be positive for LSD for as long as 120 hours after its ingestion, such studies are too complex to be clinically useful and are instead most often performed in forensic examination. [43]


Studies Related to Complications and Comorbidities

Diagnostic testing should be directed at identification of complications or exclusion of comorbidities. Coagulation, total creatine phosphokinase, or serum electrolyte studies may be indicated in patients with seizures, coma, or a neuroleptic malignant syndrome–like presentation to identify coagulopathy or rhabdomyolysis or to exclude other diagnoses. Platelet dysfunction and associated bleeding have been reported in patients with large LSD overdoses. Other studies that may prove useful include the following:

  • Imaging studies - Although radiography, computed tomography (CT) scanning, or other imaging modalities are rarely needed, they may aid in identifying complications of LSD use or in excluding other diagnoses

  • Electrocardiography (ECG) - May be appropriate if coingestion is possible or if other possible causes of tachycardia must be excluded

  • Lumbar puncture - May be indicated to exclude meningitis or encephalitis