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NCT06683638
Daily Doxycycline for Early Syphillis
Phase 2 trial testing Doxycycline 200mg daily for 14 days in Syphilis in 15 participants. Currently enrolling.
26 June 2026
Quick facts
| Lead sponsor | University of Washington |
|---|---|
| Phase | Phase 2 |
| Status | Recruiting now |
| Study type | INTERVENTIONAL |
| Allocation | na |
| Design | single group |
| Masking | none |
| Primary purpose | treatment |
| Enrollment | 15 |
| Start date | 3 March 2025 |
| Primary completion | 26 June 2026 |
| Estimated completion | 26 June 2026 |
| Sites | 1 location across United States |
Drugs / interventions tested
- Doxycycline 200mg daily for 14 days — full drug profile →
Conditions studied
- Syphilis — all drugs for Syphilis →
Sponsor
University of Washington
Who can join
18 and older, any sex, with Syphilis. Patients with the condition only — healthy volunteers not accepted.
Sponsor's own description
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.
Publications & conference data
No peer-reviewed publications indexed yet for this trial.
Verify or expand the search:
- PubMed search for NCT06683638
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Related trials
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Verify against primary sources
- ClinicalTrials.gov — authoritative US registry record
- WHO ICTRP — international registry index
- EU Clinical Trials Register
- Sponsor press releases (Google)
- Trial protocol + status: ClinicalTrials.gov NCT06683638 (US National Library of Medicine, public domain)
- Drug + disease cross-links: matched in real time against Drug Landscape's normalised drug + company + condition tables
- Sponsor: as reported to ClinicalTrials.gov by University of Washington
- Last refreshed: 25 June 2025
Drug Landscape aggregates and links these public records for informational use only. Always verify against the primary source before clinical or regulatory decisions. Canonical URL: https://druglandscape.com/trial/NCT06683638.
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