Direct Observation Study of Kratom Product Effects Among Regular Consumers

January 22, 2026 updated by: Johns Hopkins University

Observing the Acute Effects Following a Single Oral Dose of Kratom and Effects Following Kratom Cessation Among Adults Who Use Regularly.

The goal of this observational clinical study is to is to learn more about how commercial kratom products affect healthy adults who consume them regularly. The main questions it aims to answer are:

  1. What are the acute physiological, subjective, and cognitive effects of kratom following participant self-administration of a single oral dose of the participants usual kratom product at the participants typical dose?
  2. What are the physiological, subjective, and cognitive effects associated with kratom product discontinuation among adults who use regularly?
  3. What are the pharmacokinetics of kratom products consumed by adults who use regularly? On the first study day: Under direct observation, participants will self-administer a single oral dose of the participants own commercial kratom product that that is regularly taken and will consume it at the participants self-selected typical dose/serving. Following this, serial blood draws and urine collection will occur along with administration of validated questionnaires, tests, and continual monitoring. After this first study day, participants will no longer be permitted to use any of the participants kratom product during the study. On study nights/days 2-3: participants will reside a clinical research unit and be observed and evaluated for kratom withdrawal syndrome.

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.

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.
Observational

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.
22

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.
  • Name: Kirsten E Smith, Ph.D.
  • Phone Number: 865-418-8177
  • Email: ksmit398@jh.edu

Study Contact Backup

  • Name: Naftali Zeilinger, B.A.
  • Phone Number: 410-550-0490
  • Email: nzeilin1@jh.edu

Study Locations

  • United States
    • Maryland
      • Baltimore, Maryland, United States, 21224
        • Recruiting
        • Johns Hopkins University
        • Contact:
        • Principal Investigator:
          • Kirsten E Smith, Ph.D.
        • Contact:
          • Naftali Zeilinger, B.A.
          • Phone Number: (410) 870-9227
          • Email: nzeilin1@jh.edu

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
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Healthy adults aged 21 or older who use kratom.

Description

INCLUSION CRITERIA:

  1. >21 years
  2. reporting kratom use >5 times per week for >3 months prior to study screening
  3. English language proficiency
  4. Willingness to provide requested samples of the kratom product being currently taken

EXCLUSION CRITERIA:

  1. Reports any acute adverse, unexpected, or otherwise sudden health event related to the typical kratom product dose that occurred within 30 days of screening
  2. Having ever sought medical attention for an acute adverse health event as a result of taking any kratom product.
  3. Cannot or will not provide kratom product samples in the form of an unopened package of kratom that is clearly labeled with at least the product and vendor name.
  4. Self-reports using kratom products by any other route than orally swallowing.
  5. Current physical dependence on alcohol, benzodiazepines, or opioids
  6. Reports use of fentanyl within the past month and/or has a fentanyl positive drug screen.
  7. Discordance between self-reported substance use and drug screen results obtained during screening.
  8. Lifetime or current psychotic disorder
  9. Current untreated major depressive or bipolar disorder
  10. Pregnancy or nursing
  11. Physical, psychiatric, or environmental conditions considered by study team to increase risk or undue burden (e.g., untreated hypertension, high BMI, etc.).

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

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
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.
Acute kratom exposure
Participants who regularly consume kratom will orally self-administer a single serving of the participants commercial kratom product under direct observation in order to evaluate acute physiological, subjective, and cognitive effects and determine pharmacokinetics. This will occur during the first 24 hours of study participation. Participants will undergo direct observation and assessment for after ceasing all kratom product use. Physiological, subjective, and cognitive effects during this supervised withdrawal will be assessed.
Behavioral: Effects from acute kratom exposure
Participants who regularly use commercial Kratom products will orally consume a known quantity of kratom under direct observation on first study day; following this, participants will stop kratom use for approximately 2 nights and 2.5 days for the duration of the study.

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
Peak subjective opioid withdrawal score
Time Frame: Up to 3 days
Peak score on the Subjective Opioid Withdrawal Scale (SOWS); that occurs between Study Days 1-3. Score range 0-64. 5-point scale of intensity: 0=not at all, 1=a little, 2=moderately, 3=quite a bit, 4=extremely. Higher score indicates higher intensity. SOWS will be administered at 8 time points on Study Days 1-2 and 7 time points on Study Day 3.
Up to 3 days
Time in minutes until a Subjective Opioid Withdrawal (SOWS) score of more than 11 is reached
Time Frame: up to 3 days
Time, in minutes, until at least a moderate score (of 11 or higher) is reached on the Subjective Opioid Withdrawal Scale (SOWS). SOWS will be administered at 8 time points on Study Days 1-2 and 7 time points on Study Day 3. 5-point scale of intensity: 0=not at all, 1=a little, 2=moderately, 3=quite a bit, 4=extremely. Score range 0-64. Higher score indicates higher intensity.
up to 3 days
Peak rating and changes in rating on Drug Effects Questionnaire (primary subjective outcome)
Time Frame: Up to 3 days
Drug Effects Questionnaire (DEQ) visual analogue scale (0-100) rating for DEQ item "feeling high." The DEQ will be administered at 7 timepoints on Study Day 1 and at 6 times points on Study Days 2 and 3.
Up to 3 days
Peak rating and change in rating on Drug Effects Questionnaire (primary subjective outcome)
Time Frame: Up to 3 days
Drug Effects Questionnaire (DEQ) visual analogue scale (0-100) rating for DEQ item "drug liking." The DEQ will be administered at 7 time points on Study Day 1 and at 6 times points on Study Days 2 and 3.
Up to 3 days
Changes in accuracy on psychomotor task (primary cognitive outcome)
Time Frame: Up to 3 days
The 2-minute computerized Digit Symbol Substitution Task (DSST) outcome of total number of correct responses (accuracy) within the 2-minute test window. This will evaluate cognitive performance and impairment. The DSST will be administered at 7 time points on Study Day 1 and at 6 times points on Study Days 2 and 3.
Up to 3 days
Pupil diameter nadir size as measured in millimeters (mm) (primary physiological outcome).
Time Frame: Up to 3 days
Pupil diameter in mm under stable light conditions using a pupilometer. Pupil size will be measured at 8 timepoints on Study Days 1 and 2 and at 7 timepoints on Study Day 3
Up to 3 days

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.
Johns Hopkins University

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National Institute on Drug Abuse (NIDA)
University of Florida

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: Kirsten E Smith, Ph.D., Johns Hopkins University

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.
April 1, 2024

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.
February 1, 2028

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.
February 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).
October 12, 2023

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.
October 18, 2023

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.
October 19, 2023

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.
January 23, 2026

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.
January 22, 2026

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.
January 1, 2026

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.
  • IRB00408134
  • R00DA055571 (U.S. NIH Grant/Contract)

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

No

Studies a U.S. FDA-regulated device product

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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