The Effects of Psilocybin and LSD on Cluster Headache: A Series of 53 Cases
R. Andrew Sewell, MD; John H. Halpern, MD

Objective: To describe the use of psilocybin and lysergic acid diethylamide (LSD) for treatment of cluster headache.

Design: Patients were questioned about their use of psilocybin and LSD to treat their cluster headaches. Of 383 patients identified, 53 consented to interviews and provided medical records, thus qualifying for our primary analysis. An additional 147 respondents provided quantifiable information on use of psilocybin to terminate cluster periods, but failed to provide medical records or declined to be contacted; these individuals were included in a secondary analysis only.

Patient Selection: We included all respondents who 1) reported cluster headaches, 2) had attempted to treat their headaches with either psilocybin or LSD, 3) agreed to be contacted for evaluation by telephone or e-mail, and 4) allowed us to obtain copies of their medical records.

Main Outcome Measures: For abortive treatment, a subjective rating of "effective" - causing termination of a cluster attack in less than 20 minutes - or "ineffective". For prophylactic treatment, a subjective report of "effective" – causing total remission of the cluster period, "partially effective" – causing diminishment of cluster attack frequency or intensity, or "ineffective" – no change noted. For remission extension, subjective report of "effective" – a delayed or missed cluster period, or "ineffective" – a subsequent cluster period at the expected time.

Results: Of the 53 participants in the primary analysis, 52 had used psilocybin and nine had used LSD to treat their cluster headaches. Twenty-two (85%) of 26 psilocybin users reported that psilocybin had aborted attacks; 25 (52%) of 48 psilocybin users and seven (88%) of 8 LSD users reported termination of at least one cluster period; and 18 (95%) of 19 psilocybin users and four (80%) of five LSD users reported extension of their remission period. Twenty-two (42%) psilocybin users and two (22%) LSD users experienced therapeutic effects with sub-hallucinogenic doses. In the secondary analysis, 76 (52%) of the 147 respondents reported that psilocybin terminated at least one cluster period.

Conclusions: Our observations suggest that psilocybin and LSD may be effective in treating cluster attacks, possibly by a mechanism that is unrelated to their hallucinogenic properties. This report should not be misinterpreted as an endorsement of the use of illegal substances for self-treatment of cluster headache.