, Volume 1, Issue 1, pp 29–38 | Cite as

Comparison of the reactions induced by psilocybin and LSD-25 in man

  • Harris Isbell


  1. 1.

    The reaction induced by oral administration of 57 to 114 mcgm/kg of 0-Phosphoryl-4-hydroxy-N-dimethyltryptamine (psilocybin) has been compared with that induced by a placebo and LSD-25 (1.0 to 1.5 mcgm/kg) in 9 subjects.

  2. 2.

    Both LSD and psilocybin caused elevations in body temperature, pulse and respiratory rates, and systolic blood pressure. Threshold for elicitation of the kneejerk was decreased by both drugs.

  3. 3.

    After both drugs, abnormal mental states characterized by feelings of strangeness, difficulty in thinking, anxiety, altered sensory perception (particularly visual), elementary and true visual hallucinations, and alterations of body image were reported by the subjects.

  4. 4.

    The effects of psilocybin did not persist as long as those of LSD.

  5. 5.

    LSD is 100 to 150 times as potent as psilocybin.



Blood Pressure Placebo Systolic Blood Pressure Oral Administration Mental State 
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Copyright information

© Springer-Verlag 1959

Authors and Affiliations

  • Harris Isbell
    • 1
  1. 1.National Institute of Mental Health, Addiction Research CenterU. S. Public Health ServiceLexington

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