At risk for syphilis or chlamydia? There’s a PEP for that

Many health clinics offer free condoms, could doxycycline be next?

Astounding findings on the use of doxycycline, a common antibiotic, were recently announced by the city of San Francisco. Health officials there distributed a single dose of the drug to gay and bisexual men and transgender women as a post-exposure strategy to combat sexually transmitted infections. The results: Chlamydia and early syphilis were cut in half citywide.

The findings in San Francisco come after the federal Centers for Disease Control issued its first guidelines in October for administering doxycycline after high-risk sex, an approach known as doxyPEP. Final recommendations from the CDC on doxyPEP should come later this year.

Like the study in San Francisco, the CDC’s guidelines pertain specifically to queer men and trans women. The people given doxyPEP in San Francisco were individuals with a history of STIs or multiple sex partners; they were asked to take two 100-milligram pills of doxycycline within 72 hours of unprotected sex. The results in San Francisco comes at a time when national syphilis rates are at their highest in nearly 75 years, with chlamydia rates stagnating.

Some health officials see the San Francisco results as proof that doxyPEP works, with one epidemiologist pointing out toThe New York Times that groups not prescribed doxycycline — like cisgender women — did not see similar drops in STIs. Meanwhile, other health officers expressed skepticism, saying the reduced STI rates may be due to a high number of gay and trans people reducing their sex partners during the Mpox outbreak of 2022.

Many health officials believe any method that reduces STIs is one worth investing in, especially among high-risk, marginalized groups. For people living with HIV, other STIs present a very specific risk. Syphilis, for example, can progress more quickly in some HIV-positive people and can equate to increased HIV viral loads. Without treatment, syphilis can attack the nervous system, brain, and eyes.

Visit CDC.gov for more information on co-infections and doxyPEP.