Cluster headaches are incredibly painful and tend to occur frequently, making them particularly distressing for sufferers.
The Neurology study interviewed 53 cluster headache patients who had used psilocybin or LSD to treat their condition and found a significant number had their condition improved.
As cluster headaches are associated with the abnormal release of serotonin in the brain, and LSD and psilocybin largely work on the serotonin system, there is some theoretical basis for how the drugs might work.
However, this is a complex and poorly understood area so further controlled trials are now being planned to see whether the improvement is anything more than the placebo effect.
Interestingly, the study thanks drugs information site Erowid, as the site was involved in data collection and recruiting participants.
Research into LSD treatment for headaches was discussed in a recent edition of BBC All in the Mind.
Link to full text of paper.