There are some questions around DoxyPEP and
how this will effect drug resistance. There is no drug resistance to doxycycline within Chlamydia and Syphilis but there is some resistance within Gonorrhoea.
*Research presented at
CROI 2024 confirmed DoxyPEP's efficacy against chlamydia and syphilis in HIV-negative men was 88% and 87%, respectively (in HIV-positive men it was a bit lower), but against gonorrhoea it was only 55% effective.