Doxy-PEP Treatments Prove Successful in San Francisco, Lower STI Rates

The results are in, and prescribing the common antibiotic doxycycline as a morning-after prevention for STIs is making a difference, new reports show.

The news comes by way of "real-world studies presented this week at the Conference on Retroviruses and Opportunistic Infections (CROI 2024) in Denver," POZ.com reported.

"Doxycycline post-exposure prophylaxis – better known as doxyPEP – involves taking a single 200 milligram dose of the antibiotic within 72 hours after sex," POZ detailed.

"In October 2022, San Francisco was the first city to recommend doxyPEP for gay and bisexual men and transgender people," the report added. "Over the next year, chlamydia cases dropped steeply and syphilis also fell, but the decline in gonorrhea was minimal."

"The new results from clinical practice and population-level analyses are consistent with findings from recent clinical trials."

So impressive are the results that New York City followed suit last fall. A Nov. 9, 2023 bulletin from the NYC Department of Health and Mental Hygiene titled "Doxycycline Post-Exposure Prophylaxis (Doxy-PEP) to Prevent Bacterial Sexually Transmitted Infections," advised health care providers in the city that administration of the antibiotic after unprotected sex "has been shown in studies to reduce the incidence of syphilis, chlamydia, and gonorrhea among cisgender men who have sex with men (MSM) and transgender women with a recent history of these infections."

The Associated Press reported last October that one influential study published by the New England Journal of Medicine "found that gay men, bisexual men and transgender women with previous STD infections who took the pills were about 90% less likely to get chlamydia, about 80% less likely to get syphilis and more than 50% less likely to get gonorrhea compared with people who didn't take the pills after sex."

STIs like syphilis and gonorrhea have become harder to treat over time due to microbial resistance developing against most available antibiotics. The idea with doxy-PEP is to prevent the pathogens from successfully infecting people, rather than treating existing disease conditions. Even so, there are concerns that overuse could eventually lead to the emergence of doxycycline-resistant strains of STIs.

The San Francisco Department of Public Health's Dr. Hyman Scott addressed these concerns while taking note of the promise posed by the adoption of doxy-PEP.

"Despite reservations about widespread adoption, including concerns about antimicrobial resistance," Dr. Scott said, "the proactive distribution of doxyPEP stands poised as a powerful tool to prevent STIs across our communities."