This double-blind, placebo-controlled trial (n=65) will assess the efficacy and safety of LSD (25μg) every 3 days for 3 weeks versus placebo in treating chronic cluster headaches (CCH).
Randomized, double-blind, parallel-group Phase 2 trial comparing low‑dose LSD tartrate (25 µg per vial) given one dose every 3 days for 3 weeks (7 doses) versus matching placebo in adults with chronic cluster headache.
Design includes a 4‑week baseline observation period, 3‑week treatment period and 5‑week post‑treatment observation to assess acute and sustained effects; primary outcome is reduction in attack frequency at end of treatment.
Secondary objectives include safety, exposure–response exploration and cost‑effectiveness; background rationale arises from limited uncontrolled evidence suggesting low‑dose LSD may reduce attack frequency in refractory chronic cluster headache.
LSD tartrate equivalent to 25 µg LSD base; one dose every 3 days for 3 weeks (7 doses).
25 µg LSD base per vial
Placebo vial matched to verum; one vial every 3 days for 3 weeks (7 doses).
Matching placebo vial