An Early Phase 1 interventional study of Active Cannabis and Placebo Cannabis in Sciatica, Lumbar Radiculopathy and Lower Back Pain, sponsored by University of California, San Diego. Recruiting at 1 site in United States. Open to participants aged 21 Years to 65 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-06-03.
Sponsored by University of California, San Diego · Early Phase 1, Interventional, and Basic science
Chronic low back pain is a common and disabling condition that affects millions of people in the United States. Many people with chronic low back pain do not get enough relief from current treatments. Cannabis may help reduce pain, but researchers do not fully understand how it affects the brain in people with chronic pain. The purpose of this study is to examine how inhaled cannabis changes brain activity and reduces pain in people with chronic low back pain. Results from this study may help researchers better understand how cannabis works for pain and support the development of improved pain treatments.
Chronic low back pain is one of the most common causes of pain and disability in adults. Unfortunately, treatments that can directly reduce chronic low back pain remain limited. Cannabis has shown promise for pain relief, but researchers do not yet fully understand how it affects the brain or reduces pain in people with chronic pain.
The purpose of this study is to examine how inhaled (vaporized, not smoked) cannabis affects pain responses and brain activity in adults with chronic low back pain. Researchers will compare the effects of cannabis containing tetrahydrocannabinol (THC) to a placebo cannabis containing 0% THC.
This study involves one visit to the Keck Center for Functional MRI at UC San Diego. Participants will complete screening procedures, questionnaires, and pain testing using heat stimulation applied to the calf. Participants will be trained to rate their pain intensity and unpleasantness. A straight leg raise maneuver will also be performed to assess low back pain and any pain radiating down the leg.
Participants will inhale either THC-containing cannabis or placebo cannabis (no THC) using a vaporization device under study staff supervision. Brain imaging, heat pain testing, leg raise assessments, and pain ratings will be collected before and after cannabis administration to evaluate changes in pain processing and brain activity. Researchers will also assess self-reported pain, mood, sleep, stress, and cannabis-related effects using standardized questionnaires.
This study may improve understanding of how cannabis influences the brain and pain systems in people with chronic low back pain, and findings may help support the development of improved treatments for chronic pain.
149 studies on the registry are indexed under Sciatica; 31 are open to participants now.
This study's planned enrollment of 100 is above the median of 68 across 122 interventional studies indexed under Sciatica.
Browse Sciatica studies →University of California, San Diego is the lead sponsor of 980 studies on the registry; 195 are open to participants now.
Of its 113 completed or terminated interventional studies of FDA-regulated products, 71 (63%) have results posted.
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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.
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.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
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.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will be administered 400mg of vaporized cannabis (5.1%) before pain testing and fMRI.
Drug: Active Cannabis
Participants will be administered 400mg of vaporized cannabis (\<.1%) before pain testing and fMRI.
Drug: Placebo Cannabis
400 mg of vaporized and inhaled active cannabis (5.1%)
400 mg of vaporized and inhaled placebo cannabis (\<.1%)
Also known as: Non-Active cannabis
Cerebral Blood Flow (CBF)
Changes in brain blood flow and oxygen levels will be measured using non-invasive MRI-based brain imaging methods. These scans will assess how much blood is reaching brain tissue and how oxygen levels in the brain change over time.
Time frame: All data will be collected at the single study session (Day 1).
Pain Ratings
Pain ratings will be assessed in response to noxious heat stimulation. Pain intensity and pain unpleasantness will be measured using a 0-10 Visual Analog Scale (VAS), where 0 indicates "no pain" and 10 indicates "most intense imaginable pain" or "most unpleasant imaginable pain." Higher scores indicate greater pain intensity or unpleasantness. Subjective response to cannabis will be assessed using a 0-10 Numeric Rating Scale (NRS), with higher scores indicating greater subjective effects.
Time frame: All data will be collected at the single study session (Day 1).
Neurochemical Metabolites
We will use a specialized, non-invasive brain scan called proton magnetic resonance spectroscopy (1H-MRS) to measure certain brain chemicals linked to pain processing, including glutamate, GABA, and myo-inositol. The scan uses radiofrequency signals (sim
Time frame: All data will be collected at the single study session (Day 1).
Respiration Rate
Changes in breathing rate may be associated with pain relief and improved well-being. Breathing rate will be monitored continuously in real time to ensure accurate data collection.
Time frame: All data will be collected at the single study session (Day 1).
THC Concentrations
THC concentrations will be measured to evaluate the relationship between THC levels and pain relief.
Time frame: All data will be collected at the single study session (Day 1).
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