Obsessive-Compulsive DisorderPhase 2NCT04899687
Study of Dextromethorphan in OCD and Related Disorders
A Phase 2 study testing Fluoxetine and Dextromethorphan in people with Obsessive-Compulsive Disorder and Illness Anxiety Disorder, run by Stanford University at 1 site in United States.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Obsessive-Compulsive Disorder, Illness Anxiety Disorder, Body Dysmorphic Disorders
- What is being tested?
- Fluoxetine and Dextromethorphan
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- 1 siteUnited States
- Study dates
- 20 Jan 2022to 1 Dec 2028
- Phase
- Phase 2
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Stanford University
Stanford, California, 94304
Alessa Gaeta, BA, 650-723-4095, ocdresearch@stanford.edu
Peter van Roessel, MD, PhD
About this study
Official title: Fluoxetine/Dextromethorphan in Obsessive-Compulsive and Related Disorders: an Open-Label Crossover Pilot Study
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.
Read the 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
- Being tested
- Fluoxetine, Dextromethorphan
- Keywords
- OCD, BDD, IAD, SSD, Fluoxetine, Dextromethorphan
- Medical subject headings
- Obsessive-Compulsive Disorder, Body Dysmorphic Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
FluoxetineDrug
Also called Prozac
Fluoxetine 20mg (or previously prescribed dose) will be taken once daily by mouth for 8 weeks
DextromethorphanDrug
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.
| Study group | Role | What they receive |
|---|---|---|
| Group A: fluoxetine then fluoxetine plus dextromethorphan | Experimental | 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. Receives: Drug: Fluoxetine; Drug: Dextromethorphan |
| Group B: fluoxetine plus dextromethorphan then fluoxetine | Experimental | 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. Receives: Drug: Fluoxetine; Drug: Dextromethorphan |
What is being measured
The primary outcome is the main question the study is designed to answer.
Improvement in OCD or related disorder symptoms as measured by the Y-BOCS
Improvement in OCD severity is measured by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), a gold standard measure of the severity of obsessions and compulsions. Variants of the Y-BOCS designed for assessment of body dysmorphic disorder or illness anxiety disorder/somatic symptom disorder will be used as appropriate. Y-BOCS scores range from 0 to 40, with higher scores indicating greater severity of symptoms. Response will be defined as a 35% reduction in Y-BOCS score.
Measured: Change from baseline will be assessed at 4 weeks and at 8 weeks.
Secondary outcomes (1)
Improvement in clinical insight as measured by the BABS
Improvement in clinical insight is measured by the Brown Assessment of Beliefs Scale (BABS), a scale assessing multiple dimensions of clinical insight as relevant to OCD and related disorders. The BABS rates multiple dimensions of clinical insight related to an identified belief. BABS scores range from 0-24, with higher scores indicating greater insight impairment. Response will be defined as a 35% reduction in BABS score.
Measured: Change from baseline will be assessed at 4 weeks and at 8 weeks.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 May 2021
- Study start20 Jan 2022
- Primary completion1 Apr 2027 (estimated)
- Study completion1 Dec 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Obsessive-Compulsive DisorderStudies of the same condition, open and under way.
- More trials run by Stanford UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- After signing consent and baseline assessments, participants will be randomized 1:1 to Group A or Group B for the purposes of sequencing fluoxetine vs combined fluoxetine/dextromethorphan treatment periods.
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 60 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Stanford University
- Sponsor type
- University, hospital or other
- Collaborators
- Avy L. & Roberta L. Miller Foundation
- Responsible party
- Principal investigator, Peter J van Roessel, MD PhD, Stanford University
- Investigators
- Peter J van Roessel, MD PhD, Principal investigator, Stanford University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04899687
- Sponsor's protocol ID
- 60569
- Status last verified
- May 2026
- First submitted
- 13 May 2021
- Last updated
- 20 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 20 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Fluoxetine/Dextromethorphan in Obsessive-Compulsive and Related Disorders: an Open-Label Crossover Pilot Study
- ClinicalTrials.gov ID
- NCT04899687
- Acronym / sponsor ID
- 60569
- Conditions
- Obsessive-Compulsive Disorder, Illness Anxiety Disorder, Body Dysmorphic Disorders, Somatic Symptom Disorder
- Keywords
- OCD, BDD, IAD, SSD, Fluoxetine, Dextromethorphan
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 60 participants (estimated)
- Lead sponsor
- Stanford UniversityUniversity, hospital or other
- Collaborators
- Avy L. & Roberta L. Miller Foundation
- Study start
- 20 Jan 2022 (actual)
- Primary completion
- 1 Apr 2027 (estimated)
- Study completion
- 1 Dec 2028 (estimated)
- First posted
- 24 May 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
- Model description
- After signing consent and baseline assessments, participants will be randomized 1:1 to Group A or Group B for the purposes of sequencing fluoxetine vs combined fluoxetine/dextromethorphan treatment periods.
| Arm | Type | Receives |
|---|---|---|
| Group A: fluoxetine then fluoxetine plus dextromethorphan | Experimental | Drug: Fluoxetine, Drug: DextromethorphanGroup 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 B: fluoxetine plus dextromethorphan then fluoxetine | Experimental | Drug: Fluoxetine, Drug: DextromethorphanGroup 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. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- 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
Key exclusion criteria (5 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| FluoxetineAlso: ProzacFluoxetine 20mg (or previously prescribed dose) will be taken once daily by mouth for 8 weeks | Drug | Group A: fluoxetine then fluoxetine plus dextromethorphan, Group B: fluoxetine plus dextromethorphan then fluoxetine |
| DextromethorphanDextromethorphan, 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. | Drug | Group A: fluoxetine then fluoxetine plus dextromethorphan, Group B: fluoxetine plus dextromethorphan then fluoxetine |
Primary outcome
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.
Improvement in OCD severity is measured by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), a gold standard measure of the severity of obsessions and compulsions. Variants of the Y-BOCS designed for assessment of body dysmorphic disorder or illness anxiety disorder/somatic symptom disorder will be used as appropriate. Y-BOCS scores range from 0 to 40, with higher scores indicating greater severity of symptoms. Response will be defined as a 35% reduction in Y-BOCS score.
1 secondary outcome
Improvement in clinical insight as measured by the BABS
Time frame: Change from baseline will be assessed at 4 weeks and at 8 weeks.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 20 May 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Peter J van Roessel, MD PhD principal investigator
Stanford University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing Fluoxetine and Dextromethorphan in people with Obsessive-Compulsive Disorder and Illness Anxiety Disorder, run by Stanford University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 20 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Alessa Gaeta, BA (650 497 2578, ocdresearch@stanford.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the 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.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 20 May 2026.