Recruiting
Phase 2

Dextromethorphan

Sponsor:

Stanford University

Code:

NCT04899687

Conditions

Obsessive-Compulsive Disorder

Illness Anxiety Disorder

Body Dysmorphic Disorders

Somatic Symptom Disorder

Eligibility Criteria

Sex: All

Age: 18 - 65

Healthy Volunteers: Not accepted

Interventions

Fluoxetine

Dextromethorphan

Study Details

Brief summary:

The purpose of the study is to assess the tolerability and efficacy of dextromethorphan in combination with fluoxetine for symptom relief in OCD and related disorders.

Conditions

Obsessive-Compulsive Disorder

Illness Anxiety Disorder

Body Dysmorphic Disorders

Somatic Symptom Disorder

Study ID

NCT04899687

Start date

Jan 20, 2022

Status verified date

May, 2026

Completion date

Dec 1, 2028

Anticipated

Primary completion date

Apr 1, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 65

Healthy Volunteers: Not accepted

Inclusion Criteria:

  • Diagnosis of obsessive-compulsive disorder (OCD), body dysmorphic disorder (BDD), illness anxiety disorder (IAD) or somatic symptom disorder (SSD)
  • Living within California
  • Capacity to provide informed consent

Exclusion Criteria:

  • Current bipolar disorder or psychotic disorder
  • Active moderate or severe substance use disorder, lifetime severe substance use disorder
  • Pregnant or nursing women
  • Use of prescribed psychotropic medications other than fluoxetine for 2 weeks prior to study start
  • Having commenced OCD-targeted exposure and response-prevention (ExRP) psychotherapy within 2 months of study start

Study Design

Enrollment

60 participants

Anticipated

Allocation

Randomized

Intervention Model

Crossover

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Group A: fluoxetine then fluoxetine plus dextromethorphan

Group A participants will take fluoxetine 20mg (or prior dose) daily for 4 weeks, and will then continue fluoxetine while adding over the counter dextromethorphan, with doses increasing weekly as tolerated, for 4 weeks.

experimental: Group B: fluoxetine plus dextromethorphan then fluoxetine

Group B participants will take fluoxetine 20mg (or prior dose) daily together with over the counter dextromethorphan, with doses increasing weekly as tolerated, for 4 weeks, and then will stop dextromethorphan, continuing fluoxetine alone for 4 weeks.

Interventions

Fluoxetine

Fluoxetine 20mg (or previously prescribed dose) will be taken once daily by mouth for 8 weeks

Dextromethorphan

Dextromethorphan, an over-the-counter cough suppressant, will be taken by mouth twice daily for four weeks of the study, starting at 15mg per dose, and increasing weekly as tolerated to a maximum of 60mg per dose.

Primary outcome measure

  • Improvement in OCD or related disorder symptoms as measured by the Y-BOCS [ Time Frame: Change from baseline will be assessed at 4 weeks and at 8 weeks. ]

Central Contacts and Locations

Central contacts

Alessa Gaeta, BA

650 497 2578ocdresearch@stanford.edu

Locations

Stanford University

Recruiting

Stanford, California, United States, 94304

Contacts

Alessa Gaeta, BA

650-723-4095ocdresearch@stanford.edu

Principal Investigator:

Peter van Roessel, MD, PhD

More Information

Sponsor

Stanford University

Last update posted

May 20, 2026

Last verified

May, 2026

Keywords

  • OCD
  • BDD
  • IAD
  • SSD
  • Fluoxetine
  • Dextromethorphan

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by Stanford University on 2026-05-20.