Doxycycline for STDs

Doxycycline is a first-line treatment for chlamydia, typically taken as a multi-day course (unlike azithromycin's single-dose option), and is also used for some cases of non-gonococcal urethritis and other bacterial infections outside the STD space entirely.

Doxycycline post-exposure prophylaxis (DoxyPEP) is a newer approach where a dose is taken after condomless sex, specifically to reduce the risk of acquiring chlamydia, gonorrhea, and syphilis. Clinical trial data, particularly in studies involving men who have sex with men and transgender women, has shown meaningful reductions in bacterial STI rates with this approach, and public health guidance has started incorporating it as an option for people at higher ongoing risk. This is a doctor-guided decision based on individual risk factors, not something to self-initiate — and it's specifically for bacterial STDs, with no effect on viral infections like HIV or herpes.