Superiority of On-demand PrEP Versus PEP on Using Doxycycline for Preventing STI in MSM

Participants in the DoxyODPrEP arm would be instructed to take two doxycycline hyclate 100mg capsules orally 2-24 hours before sex, and one 100mg capsule each 24 and 48 hours after loading dose. If they have sex within 48 hours after the loading dose, they would be asked to continue a daily 100mg until two days after the last sex

Participants in the DoxyPEP arm would be instructed to take two doxycycline hyclate 100mg capsules orally within 24 hours and up to 72 hours after each sex.