Daily Doxycycline for Early Syphillis
Public ClinicalTrials.gov record NCT06683638. Field values are reproduced from the official study page; the official ClinicalTrials.gov record remains the source of truth for eligibility, enrollment, and contact information.
Data is sourced from official ClinicalTrials.gov public API records. Always review the official ClinicalTrials.gov record for the latest information.
Brief summary
Reproduced verbatim from the official ClinicalTrials.gov record. Not medical advice.
The goal of this clinical trial is to learn if doxycycline taken as 200mg daily for 14 days is effective to treat early stage syphilis. This is different from how doxycycline is typically used for syphilis because the full doxycycline dose will be taken at the same time of day, rather than split up into a twice daily regimen. Lab data support that taking the medication as a single daily dose should be effective as treatment, but it has not been studied clinically. The main question this study aims to answer is: Is doxycycline taken as a single daily dose of 200mg for 14 days an effective treatment for early syphilis based on a combined outcome of clinical improvement and blood test improvement? Participants will: 1. Take doxycycline 200mg daily for 14 days 2. Submit oral and rectal swabs that test for syphilis bacteria every other day for 2 weeks, returned by mail 3. Complete 2 brief online surveys over the first 2 weeks 4. Return to the clinic for an interview and blood draw every 3 months for a maximum of 3 study visits, including the first visit The investigators will compare the percentage of participants in the study who have response to treatment by 6 months to that of persons who have received standard (CDC-recommended) regimens. To do this, the investigators will calculate response percentage estimates following a shot of long-acting penicillin or 14 days of doxycycline 100mg twice daily from 60-person samples from the sexual health program's records.
Study identification
- NCT ID
- NCT06683638
- Recruitment status
- Recruiting
- Study type
- Interventional
- Phase
- Phase 2
- Enrollment
- 15 participants
Conditions and interventions
Conditions
Eligibility (public fields only)
- Age range
- 18 Years and older
- Sex
- All
- Healthy volunteers
- Healthy volunteers not accepted
This page does not interpret eligibility. Detailed inclusion and exclusion criteria are on the official ClinicalTrials.gov record.
Study timeline
- Start date
- Mar 2, 2025
- Primary completion
- Jun 25, 2026
- Completion
- Jun 25, 2026
- Last update posted
- Jun 24, 2025
2025 – 2026
United States locations
- U.S. sites
- 1
- U.S. states
- 1
- U.S. cities
- 1
| Facility | City | State | ZIP | Site status |
|---|---|---|---|---|
| Public Health Sexual Health Clinic | Seattle | Washington | 98104 | Recruiting |
Site contact phone numbers, emails, and investigator names are intentionally not displayed here. Open the official ClinicalTrials.gov record for site contact information.
About this trial record page
- What this page shows
- Public field values for ClinicalTrials.gov record NCT06683638, including study identification, conditions, interventions, eligibility (age, sex, healthy volunteer), timeline, and U.S. site list.
- What this page does not do
- No medical advice, eligibility judgments, treatment recommendations, study quality scoring, or AI-generated medical summaries. No site contact phone numbers, emails, or investigator names.
- Where the data comes from
- Sourced from the official ClinicalTrials.gov public API. The official record is the source of truth.
- Last refresh
- Last update posted Jun 24, 2025 · Synced Sep 10, 2026
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Open the official record
The complete protocol, eligibility criteria, and contact information for NCT06683638 live on ClinicalTrials.gov.