PEP Topic 

Psilocybin is a naturally occurring psychedelic compound found in various species of mushrooms. Psilocybin is rapidly metabolized to psilocin, which is a potent agonist at serotonin receptor activation, directly correlated with human hallucinogenic activity. It has been examined in the treatment of anxiety in patients with advanced stage cancer.

Effectiveness Not Established

Research Evidence Summaries

Grob, C.S., Danforth, A.L., Chopra, G.S., Hagerty, M., McKay, C.R., Halberstadt, A.L., & Greer, G.R. (2011). Pilot study of psilocybin treatment for anxiety in patients with advanced-stage cancer. Archives of General Psychiatry, 68, 71–78.

doi: 10.1001/archgenpsychiatry.2010.116

Study Purpose:

To explore the safety and efficacy of psilocybin in patients with advanced cancer and anxiety

Intervention Characteristics/Basic Study Process:

Each participant received two treatment sessions, one with placebo and one with psilocybin, provided in random order. A niacin placebo was used, and psilocybin was given orally at a 0.2 mg/kg dosage. Sessions took six hours, provided in a clinical research unit with direct constant staff observation. Vital signs were measured 30 minutes before drug ingestion and at hourly intervals. All had continuous Holter monitoring. Study instruments were administered the day before each session, the day after the session, two weeks after sessions, and at monthly intervals for the next six months. At the end of each session, participants discussed their experiences. Participants were followed via monthly phone calls.

Sample Characteristics:

  • The study reported on a sample of 12 patients.
  • Patient age range was 36–58 years (average not reported).
  • The sample was 92% female and 8% male.
  • All patients had advanced stage cancer, including breast, colon, ovarian, peritoneal, salivary gland, and multiple myeloma. Duration of diagnosis ranged from 2 months to 18 years. All patients had a DSM-IV diagnosis of acute stress disorder, generalized anxiety disorder, or adjustment disorder with anxiety.
  • Patients were excluded if they had central nervous system disease, cardiovascular illness, other severe comorbid uncontrolled conditions, or lifetime history of psychiatric disorders.
  • Of the sample, 75% had prior experience using hallucinogenic agents, including LSD, mushrooms, peyote, and ayahuasca.


  • Single site
  • Outpatient setting
  • California

Phase of Care and Clinical Applications:

  • Patients were undergoing end-of-life care.
  • The study has clinical applicability for end-of-life and palliative care.

Study Design:

A within-subjects, double-blind, placebo-controlled study design was used.

Measurement Instruments/Methods:

  • Beck Depression Inventory (BDI)
  • Profile of Mood States (POMS)
  • State-Trait Anxiety Inventory (STAI)
  • Brief Psychiatric Rating Scale
  • Five Dimension Altered States of Consciousness Profile


All patients completed three months of follow-up, and eight patients completed six months of follow-up. Psilocybin induced a mild but statistically significant elevation of heart rate and diastolic blood pressure compared to the placebo. Heart rate peaked at two hours, with a peak rate of 81.5 on average. Blood pressure also peaked at two hours at a mean of 138.9 systolic, compared to a baseline average of 117. Holter monitor recording showed no significant differences from placebo session results. BDI scores dropped by almost 30% from the first session to one month after the second session (p = 0.05). This difference was sustained for six months (p = 0.03). Improvement in POMs were observed in 11 patients after psilocybin administration. STAI results showed improvement in state anxiety at one month (p = 0.001) and three months (p = 0.03).


As administered here, psilocybin administration was associated with sustained improvement in depression and anxiety, with no serious cardiovascular adverse effects.


  • The study sample was small, with less than 30 patients.
  • Patients did know the difference in experience between psilocybin and placebo, so patient blinding was not realistically accomplished.
  • Given the results with potential of long-term effect, the control condition was not really valid, except for immediate vital signs responses.

Nursing Implications:

Studies done in the 1960s and 1970s showed that hallucinogens had therapeutic benefits for patients with terminal cancer, and this pilot feasibility study shows similar results. As provided here, administration of psilocybin was accomplished in a clinical research unit with constant staff monitoring, which may not be widely practical in terms of cost and manpower. Further research in the use of hallucinogens in patients with anxiety and depression are needed to determine the most appropriate dosages, and whether they can be used in a less controlled setting for therapeutic benefit. The majority of patients had prior experience with hallucinogens; it is not clear if similar results would be seen if patients had no such prior experience.