A Randomized Controlled Trial of Doxycycline Post Exposure Prophylaxis to Prevent Incident Bacterial STIs Among Women in the United States

The bacterial sexually transmitted infections (STIs) chlamydia, gonorrhea, and syphilis cause multiple adverse outcomes in women, and prevention strategies are critically needed. This project will determine the efficacy of doxycycline post-exposure prophylaxis (doxy PEP) to prevent STIs among women through a phase IV, open-label, randomized controlled trial.

Inclusion Criteria: * Female * Aged 18-35 * Reporting condomless vaginal sex with men AND least one of the following: 1. diagnosis of CT, gonorrhea, syphilis, or trichomonas in the past year 2. reporting 2 or more sexual partners in the past 6 months * Plan to continue to be sexually active over the next year * Have smartphone and be willing to engage with an app * If HIV+: Viral load\200 cells/mm3 Exclusion Criteria: * Pregnant, nursing, or intending to become pregnant * Reported allergy to tetracyclines * Liver disease or end-stage renal disease * Non-English Speaking * Taking concomitant medications which may impact doxycycline metabolism (e.g., systemic retinoids, antacids, barbiturates, carbamazepine, phenytoin, iron, warfarin, rifampin) * Not willing to take doxy PEP or comply with study procedures * Unable to provide informed consent