Cannabidiol monotherapy for treatment-resistant schizophrenia

J Psychopharmacol. 2006 Sep;20(5):683-6. doi: 10.1177/0269881106060967. Epub 2006 Jan 9.


Cannabidiol (CBD), one of the major products of the marijuana plant, is devoid of marijuana's typical psychological effects. In contrast, potential antipsychotic efficacy has been suggested based on preclinical and clinical data (Zuardi et al., 2002). In this report, we further investigated the efficacy and safety of CBD monotherapy in three patients with treatment-resistant schizophrenia (TRS). This was an in-patient study. All patients were given placebo for the initial 5 days, and from the 6th to 35th day (inclusive) they received CBD (initial oral dose of 40 mg reaching 1280 mg/day). On the 36th day, CBD treatment was discontinued and replaced by placebo for 5 days, which was subsequently switched to olanzapine for over 15 days. Efficacy, tolerability and side effects were assessed. One patient showed mild improvement, but two patients didn't show any improvement during CBD monotherapy. All patients tolerated CBD very well and no side effects were reported. These preliminary data suggest that CBD monotherapy may not be effective for TRS.

Publication types

  • Case Reports
  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aggression / drug effects
  • Antipsychotic Agents / adverse effects
  • Antipsychotic Agents / therapeutic use*
  • Behavior / drug effects
  • Cannabidiol / adverse effects
  • Cannabidiol / therapeutic use*
  • Drug Resistance
  • Humans
  • Male
  • Psychiatric Status Rating Scales
  • Schizophrenia / drug therapy*
  • Schizophrenic Psychology
  • Substance Withdrawal Syndrome / psychology


  • Antipsychotic Agents
  • Cannabidiol