Doxycycline Prophylaxis for Prevention of Sexually Transmitted Infections

Recruiting now · Phase 4

Conditions studied: Gonorrhea, Chlamydia, Syphilis, Sexually Transmitted Infections (STIs)

In brief

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.

Key facts

Study ID

NCT06738407

Run by

Westat

People needed

760

Starts

2026-02-27

Expected to finish

2028-06-15

Last updated by the study team

2026-05-15

Who can join

Age: 13 and older, up to 29. Sex: female. Healthy volunteers: not accepted.

You may qualify if…

• 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.

You may not qualify if…

• 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.

Where it is running

• University of Florida — Tampa, Florida, United States (enrolling)
• San Francisco Department of Public Health — San Francisco, California, United States (enrolling)
• University Illinois Chicago — Chicago, Illinois, United States (enrolling)
• Children's National Medical Center — Washington D.C., District of Columbia, United States (enrolling)
• St. Jude Children's Research Hospital — Memphis, Tennessee, United States (enrolling)
• Baylor College of Medicine — Houston, Texas, United States (enrolling)
• Penn Prevention — Philadelphia, Pennsylvania, United States
• Tulane University — New Orleans, Louisiana, United States
• Ponce de Leon — Atlanta, Georgia, United States
• UCLA Care — Los Angeles, California, United States
• Johns Hopkins University — Baltimore, Maryland, United States
• Harlem Prevention Center — New York, New York, United States
• Chapel Hill — Chapel Hill, North Carolina, United States

Full record on ClinicalTrials.gov

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