Recruiting

DoxycyclineDoxycycline Prophylaxis for Prevention of Sexually Transmitted Infections

Sponsor:

Westat

Code:

NCT06738407

Conditions

Gonorrhea

Chlamydia

Syphilis

Sexually Transmitted Infections (STIs)

Eligibility Criteria

Sex: Female

Age: 13 - 29

Healthy Volunteers: Not accepted

Interventions

Doxycycline hyclate delayed released 200 mg

Doxycycline hyclate delayed released 200 mg weekly

Per standard of care with quarterly STI testing/treatment and sexual health counseling

Study Details

Brief summary:

The goal of this open-label, randomized trial is to assess the efficacy of doxycycline prophylaxis in reducing incidences of bacterial sexually transmitted infections (STIs) among adolescent and young adult females while also evaluating acceptability and antimicrobial resistance in order to inform public health policy.

Conditions

Gonorrhea

Chlamydia

Syphilis

Sexually Transmitted Infections (STIs)

Study ID

NCT06738407

Start date

Feb 27, 2026

Status verified date

May, 2026

Completion date

Jun 15, 2028

Anticipated

Primary completion date

Jun 15, 2028

Anticipated

Eligibility Criteria

Sex: Female

Age: 13 - 29

Healthy Volunteers: Not accepted

Inclusion Criteria:

Age 13-29 years, inclusive;
Self-reports GC, CT, and/or early syphilis diagnosis in the 12 months prior to screening;
Self-reports condomless (oral, vaginal, and/or anal) intercourse at least once in the 30 days prior to screening
Is at least 45 kilograms (99.2 pounds) in weight
Fluent in English (able to read, speak, and understand English);
Willing to undergo all required study procedures; and
Willing to provide written informed consent to participate in the study.

Exclusion Criteria:

Is male;
Is pregnant, breastfeeding, or planning to become pregnant in the next 12 months;
Documented history of tetracycline allergy or self-reports an allergy to tetracyclines;
Current or anticipated use of a medication (e.g., barbiturates, phenytoin, lithium, carbamazepine, systemic retinoids, warfarin) with a contraindicated interaction to doxycycline ;
Current or planned use of doxycycline for a prolonged period (> 2 weeks) in the 30 days prior to enrollment, including current prescription for doxycycline for STI prophylaxis;
Prolonged antibiotic use (> 2 weeks) within the last 30 days prior to enrollment;
Co-enrollment in any other concurrent interventional research or studies that may interfere with this study, such as an STI prevention trial, unless approved by Protocol Team in writing;
Does not have consistent access (or anticipated weekly access for 52 weeks of survey completion) to smartphone that can access the HMP app; or
Any other medical condition, medical/behavioral intervention, or other conditions that, in the opinion of the clinical site Project Lead (PL)/Investigator of Record (IoR) or designee, could interfere with adherence to study procedures or compromise interpretation of study results.

Study Design

Enrollment

760 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Prevention

Interventions and Outcome Measures

Arms

experimental: On-demand doxyPEP

Participants will take by mouth doxycycline 200 mg as soon as possible and within 72 hours after any condomless oral, vaginal, and/or anal sex in addition to standard of care STI testing/treatment and sexual health counseling.

experimental: Weekly doxycycline

Participants will take by mouth doxycycline 200 mg weekly regardless of sexual activity in addition to standard of care STI testing/treatment and sexual health counseling.

other: Quarterly STI testing/treatment and sexual health counseling

Participants will be followed per standard of care with quarterly STI testing/treatment and sexual health counseling.

Interventions

Doxycycline hyclate delayed released 200 mg

200 mg of doxycycline taken by mouth as soon as possible and within 72 hours after any condomless oral, vaginal, and/or anal sex along with STI screening and sexual health counseling

Doxycycline hyclate delayed released 200 mg weekly

200 mg of doxycycline taken by mouth weekly regardless of sexual activity along with STI screening and sexual health counseling

Per standard of care with quarterly STI testing/treatment and sexual health counseling

Quarterly STI testing/treatment and sexual health counseling

Primary outcome measure

Combined incidence of GC, CT, and/or early syphilis infection [ Time Frame: One (1) year ]

Central Contacts and Locations

Central contacts

Nancy Liu

718-980-3937 NancyLiu@westat.com

Erin Ricketts

240-453-2786 ErinRicketts@westat.com

Locations

San Francisco Department of Public Health

Recruiting

San Francisco, California, United States, 94102

Contacts

Emily Schaeffer

628-217-7456 emily.schaeffer@sfdph.org

Principal Investigator:

Albert Liu

Children's National Medical Center

Recruiting

Washington D.C., District of Columbia, United States, 20010

Contacts

Justin Unternaher

202-476-1030 junternahe@childrensnational.org

Principal Investigator:

Natella Rakhmanina

University of Florida

Recruiting

Tampa, Florida, United States, 33612

Contacts

Elizabeth Enriquez-Bruce

813-250-2574 enriquezbruce@usf.edu

Principal Investigator:

Patricia Emmanuel

University Illinois Chicago

Recruiting

Chicago, Illinois, United States, 60612

Contacts

Rachel Jackson

312-996-6018 rjacks34@uic.edu

Principal Investigator:

Kelly Bojan

St. Jude Children's Research Hospital

Recruiting

Memphis, Tennessee, United States, 38015

Contacts

Mary Dillard

901-595-4083 Mary.dillard@stjude.org

Principal Investigator:

Aditya Gaur

Baylor College of Medicine

Recruiting

Houston, Texas, United States, 77030

Contacts

Litty Koshy

832-822-1038 Litty.Koshy@bcm.edu

Principal Investigator:

Mary Paul

More Information

Sponsor

Westat

Last update posted

May 15, 2026

Last verified

May, 2026

Keywords

Sexually Transmitted Infections
STIs
Doxycycline Prophylaxis
Doxycycline

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-09. This information was provided to ClinicalTrials.gov by Westat on 2026-05-15.