Years after it was first proven to work, a new tool for preventing sexually transmitted infections (STIs) is on the brink of entering mainstream medicine.
That tool is doxyPEP, an antibiotic that works like a morning-after pill — but instead of preventing pregnancy within hours of unprotected sex, it prevents STIs like chlamydia and syphilis.
Sexually transmitted infections have been rising in recent years, with syphilis in particular spreading explosively, and doxyPEP could help turn back the tide. Rising STI rates are costing dollars and lives: The CDC estimates that the US spent $1.1 billion on bacterial STIs in 2018, and 166 infants died in 2021 as a consequence of a syphilis epidemic affecting women of childbearing age.
And while San Fransisco is ready to roll out doxyPEP more broadly, public health agencies like the CDC haven’t yet issued full-throated recommendations in support of the pill’s use. What’s the holdup?
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The major obstacle is the fear that doing so will touch off a perilous game of infectious disease whack-a-mole — that in trying to mitigate one public health crisis, we’ll worsen another one.
Doxycycline, the medication in doxyPEP, is an antibiotic. Worldwide antibiotic resistance is a major problem — and doxyPEP runs the hypothetical risk of exacerbating it. Disease-causing bacteria can evolve resistance when exposed to certain antibiotics, becoming more dangerous.
