A Phase 2 interventional study of Lysergic Acid Diethylamide and Placebo in Cluster Headache, sponsored by University Hospital, Basel, Switzerland. Active, not recruiting at 1 site in Switzerland. Open to participants aged 25 Years to 75 Years. Per ClinicalTrials.gov, last updated 2026-11-03.
Sponsored by University Hospital, Basel, Switzerland · Phase 2, Interventional, and Treatment
Background: After no official research in humans in the last 40 years, research and therapeutic uses of the serotonergic psychedelic lysergic acid diethylamide (LSD) are now re-recognized and include its use in brain research, alcoholism, anxiety associated with terminal illness, and treatment of headache disorders. Specifically, LSD has been reported to abort attacks, to decrease frequency and intensity of attacks, and to induce remission in patients suffering from cluster headache (CH).
Objective: To investigate the effects of an oral LSD pulse regimen (3 x 100 µg LSD in three weeks) in patients suffering from CH compared with placebo.
Design: Double-blind, randomized, placebo-controlled two-phase cross-over study design.
Participants: 30 patients aged ≥ 25 and ≤ 75 years with chronic or episodic CH with predictable periods lasting approximately 2 months and attacks responding to oxygen.
Main outcome measures: Changes in frequency and intensity of CH attacks assessed with a standardized headache diary Significance: CH is often rated as the most painful of all primary headaches, which not only causes significant disability, but is also associated with enormous personal, economic, and psychiatric burden. At the moment, there is no specific treatment available for CH, but serotonergic compounds represent an important drug class, especially in the abortive management of cluster attacks. However, there is a need for new treatment approaches, as CH is also often insufficiently managed with available medication. This study will evaluate the potential benefit and safety of a treatment with LSD for patients with CH.
123 studies on the registry are indexed under Cluster Headache; 26 are open to participants now.
This study's planned enrollment of 30 is below the median of 42 across 90 interventional studies indexed under Cluster Headache.
Browse Cluster Headache studies →University Hospital, Basel, Switzerland is the lead sponsor of 990 studies on the registry; 189 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
DSM diagnostic criteria
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Creatinine clearance (CrCl)
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Lysergic acid diethylamide (3 x 100 µg LSD in three weeks, per os) followed by Placebo
Drug: Lysergic Acid Diethylamide · Drug: Placebo
Placebo (3 x 1 vial looking like LSD in three weeks, per os) followed by Lysergic acid diethylamide
Drug: Lysergic Acid Diethylamide · Drug: Placebo
100 µg, per os, 3 times within 3 weeks
Also known as: LSD
placebo in an identical-looking vial as LSD, per os, 3 times within 3 weeks
Change in frequency of the cluster headache attacks
assessed with a standardized headache diary, within-subjects analysis
Time frame: 8 weeks before and after pulse regimen
Change in intensity of the cluster headache attacks
assessed with a standardized headache diary, within-subjects analysis
Time frame: 8 weeks before and after pulse regimen
Episode abortion
assessed with a standardized headache diary
Time frame: through study completion, an average of 1 year
Change in duration of attacks
assessed with a standardized headache diary
Time frame: 8 weeks after pulse regimen
Time to first attack after completion of pulse regimen
assessed with a standardized headache diary
Time frame: 8 weeks after pulse regimen
Cumulative time with headache
assessed with a standardized headache diary
Time frame: 8 weeks after pulse regimen
Change in cluster period duration and interval between cluster periods
assessed with a standardized headache diary
Time frame: 8 weeks after pulse regimen
Number of attacks requiring abortive medication
assessed with a standardized headache diary
Time frame: 8 weeks after pulse regimen
Number of Attack-associated autonomic symptoms
assessed with a standardized headache diary
Time frame: 8 weeks after pulse regimen
Quality of life assessed by questionnaires: 36-item short-form health survey (SF-36)
assessment with the validated 36-item short-form health survey (SF-36), which measures health-related quality of life
Time frame: through study completion, an average of 1 year
Quality of life assessed by questionnaires: 5-level EuroQoL-5D (EQ-5D-5L)
assessment with the 5-level EuroQoL-5D (EQ-5D-5L), which is a standardized instrument developed by the EuroQol Group as a measure of health-related quality of life
Time frame: through study completion, an average of 1 year
Quality of life assessed by questionnaires: Headache Impact Test (HIT-6)
assessment with the Headache Impact Test (HIT-6), which measures the adverse impact of headache on social functioning, role functioning, vitality, cognitive functioning and psychological distress.
Time frame: through study completion, an average of 1 year
Effects on depressive /anxious symptoms assessed by questionnaires: State-trait anxiety inventory (STAI)
assessment with the State-trait anxiety inventory (STAI), which measures anxiety
Time frame: through study completion, an average of 1 year
Effects on depressive /anxious symptoms assessed by questionnaires: Generalized anxiety disorder-7 (GAD-7)
assessment with the Generalized anxiety disorder (GAD-7), which measures anxiety
Time frame: through study completion, an average of 1 year
Effects on depressive /anxious symptoms assessed by questionnaires: Hospital Anxiety and Depression Scale (HADS)
assessment with the Hospital Anxiety and Depression Scale (HADS), which measures anxiety and depression severity
Time frame: through study completion, an average of 1 year
Effects on depressive /anxious symptoms assessed by questionnaires: Beck Depression Inventory (BDI)
assessment with the Beck Depression Inventory (BDI), which measures depression
Time frame: through study completion, an average of 1 year
Effects on depressive /anxious symptoms assessed by questionnaires: Patient health questionnaire-9 (PHQ-9)
assessment with the Patient health questionnaire-9 (PHQ-9), which measures depression
Time frame: through study completion, an average of 1 year
Acute autonomic effects assessed by blood pressure
systolic and diastolic blood pressure in mmHg
Time frame: 10 hours after drug administration
Acute autonomic effects assessed by heart rate
heart rate in beats per minute
Time frame: 10 hours after drug administration
Acute autonomic effects assessed by body temperature
body temperature in °Celsius
Time frame: 10 hours after drug administration
Adverse Events
adverse events will be recorded
Time frame: through study completion, an average of 1 year
Acute psychological effects assessed by questionnaire Visual analogue scales (VAS)
assessment of subjective effects using visual analogue scales
Time frame: 10 hours after drug administration
Acute psychological effects assessed by SCQ
assessed with the states of consciousness questionnaire (SCQ)
Time frame: 10 hours after drug administration
Acute psychological effects assessed by questionnaire 5-dimensions of altered states of consciousness
assessed with the 5-dimensions of altered states of consciousness questionnaire (5D-ASC)
Time frame: 10 hours after drug administration
Persisting effects attributed to the LSD experience
assessment of persisting effects with the persisting effects questionnaire (PEQ) which assesses changes in attitude, mood, behavior and spiritual experience. The questionnaire will be completed at the beginning, after pulse regimens, and at the end of the study.
Time frame: through study completion, an average of 1 year
Change of attack frequency at the end of the study compared with baseline
pre-post study comparison in all subjects, assessed with a standardized headache diary
Time frame: through study completion, an average of 1 year
Change of attack intensity at the end of the study compared with baseline
pre-post study comparison in all subjects, assessed with a standardized headache diary
Time frame: through study completion, an average of 1 year
Change in attack frequency before and after pulse regimen
between-subjects analysis before cross-over, assessed with a standardized headache diary
Time frame: 8 weeks after first pulse regimen
Change in attack intensity before and after pulse regimen
between-subjects analysis before cross-over, assessed with a standardized headache diary
Time frame: 8 weeks after first pulse regimen
Blinding
patients and investigators will be asked at the end of a study day and and the end of the study visit to guess the drug treatment
Time frame: after study days and at the end of study visit
Expectancy
a modified 2-item version of the Credibility / Expectancy Questionnaire (CEQ) will be used
Time frame: at screening
Plan to share: No
No publications or documents are linked to this record.
Started Jan 2019 (actual). Primary completion is estimated for Oct 2027, 105 months after the start.
Since we started tracking on Sep 25, 2026, the dates moved once, on Nov 3, 2026: primary completion Dec 2025 → Oct 2027 and completion Dec 2025 → Oct 2027.
Earlier changes are on the record history on ClinicalTrials.gov ↗
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is active, not recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Lysergic Acid Diethylamide
University Hospital, Basel, Switzerland →