This article provides a comprehensive overview of Doxycycline Post-Exposure Prophylaxis (Doxy-PEP), an antibiotic used to reduce the risk of bacterial sexually transmitted infections (STIs) such as chlamydia, gonorrhea, and syphilis following condomless sex. It explains how Doxy-PEP works, the correct dosage and timing (200 mg within 24–72 hours after exposure), and who should or should not take it, including guidance for pregnant individuals. The article discusses potential side effects, interactions with other medications, and considerations regarding antibiotic resistance.