Could a single pill after sex stop STIs in women?

NCT ID NCT07704957

First seen Jul 15, 2026 · Last updated Jul 16, 2026 · Updated 1 time

Summary

This trial tests whether taking a single dose of the antibiotic doxycycline within 24 hours of condomless sex can prevent bacterial sexually transmitted infections (STIs) like chlamydia, gonorrhea, and syphilis in women aged 18–35 at increased risk. Participants are randomly assigned to receive doxycycline or standard care, and researchers track how many new STIs occur over time. If it works, this approach could offer a new prevention tool for women.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance
doxycycline taken as a single 200 mg dose within 24 hours of condomless sex
What this could lead to
If effective, this could give women a simple, on-demand pill to prevent common bacterial STIs, reducing infections and related health problems.
What could go wrong
A previous trial in women found no benefit, so results may not be positive. The study is open-label, which can bias outcomes, and long-term antibiotic use raises concerns about resistance and side effects.

This is an AI summary of the original study and may miss details. Read our disclaimer.

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Conditions

The condition(s) this trial relates to.

As listed by the trial registrant

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