THC and CBD: A Controlled Human Study Probing a Harm Reduction Strategy (THC-REDUX)

December 15, 2025 updated by: Ziva D. Cooper, PhD, University of California, Los Angeles

Interactions Between Delta-9-THC and CBD: A Controlled Human Drug-administration Study Probing a Harm Reduction Strategy

The purpose of this research is to assess the impact of CBD on the effects of THC.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Some evidence indicates that cannabidiol (CBD), a non-intoxicating cannabis component, might mitigate certain effects of THC. This study will examine possible roles for CBD in modulating THC's adverse and analgesic effects.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
30

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Male or non-pregnant and non-lactating females aged 21-55 years
  • Report cannabis use 1-7 days per week over the month prior to screening
  • Not currently seeking treatment for their cannabis use
  • History of inhaled cannabis use
  • Have a Body Mass Index from 18.5 - 34 kg/m2
  • Able to perform all study procedures
  • Must be using a contraceptive (hormonal or barrier methods)

Exclusion Criteria:

  • Meeting DSM-V criteria for severe Cannabis Use disorder (CUD) or any substance use disorder other than nicotine, caffeine, mild or moderate CUD
  • Evidence of severe psychiatric illness (e.g. mood or anxiety disorder with functional impairment or suicide risk, schizophrenia) judged by the study physician (and PI) to put the participant at greater risk of experiencing adverse events due to completion of study procedures, interfere with their ability to participate in the study, or their capacity to provide informed consent.
  • Report using other illicit drugs in the prior 4 weeks
  • Current pain
  • Pregnancy
  • Currently enrolled in another research protocol
  • Not using a contraceptive method (hormonal or barrier methods)
  • Insensitivity to the cold water stimulus of the Cold Pressor Test
  • Any disorders that might make cannabis administration hazardous as determined by evaluation physician after review of all medical assessments along with medical history.
  • Not able to speak and read English

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Placebo Comparator: Placebo
0 mg THC, 0 mg CBD
Drug: Placebo
Vaporized Placebo
Other Names:
  • Cannabis
Active Comparator: THC
20 mg THC, 0 mg CBD
Drug: THC
Vaporized THC (20 mg)
Other Names:
  • Cannabis
Active Comparator: CBD 20
0 mg THC, 20 mg CBD
Drug: CBD 20 mg
Vaporized CBD (20 mg)
Other Names:
  • Cannabis
Active Comparator: CBD 40
0 mg THC, 40 mg CBD
Drug: CBD 40 mg
Vaporized CBD (40 mg)
Other Names:
  • Cannabis
Active Comparator: CBD 80
0 mg THC, 80 mg CBD
Drug: CBD 80 mg
Vaporized CBD (80 mg)
Other Names:
  • Cannabis
Active Comparator: THC with CBD 20
20 mg THC, 20 mg CBD
Drug: THC
Vaporized THC (20 mg)
Other Names:
  • Cannabis
Drug: CBD 20 mg
Vaporized CBD (20 mg)
Other Names:
  • Cannabis
Active Comparator: THC with CBD 40
20 mg THC, 40 mg CBD
Drug: THC
Vaporized THC (20 mg)
Other Names:
  • Cannabis
Drug: CBD 40 mg
Vaporized CBD (40 mg)
Other Names:
  • Cannabis
Active Comparator: THC with CBD 80
20 mg THC, 80 mg CBD
Drug: THC
Vaporized THC (20 mg)
Other Names:
  • Cannabis
Drug: CBD 80 mg
Vaporized CBD (80 mg)
Other Names:
  • Cannabis

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Subject-rated drug effects of abuse liability
Time Frame: 3 hours
Subject ratings of "Good Drug Effect" as measured using a visual analog scale (1-100 mm)
3 hours
Analgesia as measured using the Cold Pressor Test
Time Frame: 3 hours
Pain threshold assessed using the Cold Pressor Test (percent baseline)
3 hours
Behavioral task performance as assessed by the DRUID App Score
Time Frame: 3 hours
Trough composite scores on the DRUID App
3 hours
Pharmacokinetics of THC
Time Frame: 3 hours
Peak plasma levels of THC (ng/ml)
3 hours

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of California, Los Angeles

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Ziva Cooper, PhD, University of California, Los Angeles

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 5, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 1, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 25, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 3, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 5, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
December 17, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 15, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 24-5306
  • 93306 (Other Grant/Funding Number: CA Department of Cannabis Control)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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