Study of Dextromethorphan in OCD and Related Disorders

NCT ID: NCT04899687

Last Updated: 2025-08-27

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: PHASE2
• Total Enrollment: 60 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2022-01-20
• Study Completion Date: 2026-12-01

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.

Detailed Description

Obsessive compulsive disorder (OCD) and the related disorders body dysmorphic disorder (BDD), somatic symptom disorder (SSD) and illness anxiety disorder (IAD) are psychiatric conditions characterized by recurrent, intrusive thoughts, feelings or images (obsessions or preoccupations) and repetitive or ritualized behaviors or avoidance performed to relieve obsession or preoccupation-related anxiety. They are a significant cause of mental health-related disability, and are inadequately served by available treatments.

This study tests whether an over-the-counter cough suppressant medicine, dextromethorphan, may offer symptom relief when combined with a low dose of fluoxetine, a standard prescription treatment for OCD and related disorders.

Conditions

Obsessive-Compulsive Disorder; Illness Anxiety Disorder; Body Dysmorphic Disorders; Somatic Symptom Disorder

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: TREATMENT
• Blinding Strategy: SINGLE

Study Groups

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.

Group Type: EXPERIMENTAL

Fluoxetine

Intervention Type: DRUG

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

Dextromethorphan

Intervention Type: DRUG

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.

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.

Group Type: EXPERIMENTAL

Fluoxetine

Intervention Type: DRUG

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

Dextromethorphan

Intervention Type: DRUG

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.

Interventions

Fluoxetine

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

Intervention Type: DRUG

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.

Intervention Type: DRUG

Other Intervention Names

Prozac

Eligibility Criteria

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

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 65 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Avy L. & Roberta L. Miller Foundation

UNKNOWN

Sponsor Role: collaborator

Stanford University

OTHER

Sponsor Role: lead

Responsible Party

Peter J van Roessel, MD PhD

Clinical Associate Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Peter J van Roessel, MD PhD

Role: PRINCIPAL_INVESTIGATOR

Stanford University

Locations

Stanford University

Stanford, California, United States

Site Status: RECRUITING

Countries

United States

Central Contacts

Pavithra Mukunda, MS

Role: CONTACT

ocdresearch@stanford.edu

650 497 2578

Facility Contacts

Pavithra Makunda, MS

Role: primary

ocdresearch@stanford.edu

650-723-4095

Other Identifiers

60569

Identifier Type: -

Identifier Source: org_study_id