On October 30, 2026, aidsmap reported a modelling study estimating how much doxycycline Europe is using for doxyPEP, the single 200mg dose taken within 72 hours of condomless sex to prevent bacterial STIs. The European AIDS Treatment Group republished the summary on November 4. The researchers focused on gay, bisexual and other men who have sex with men who take PrEP, because that group probably accounts for most current doxyPEP users and its size can be estimated from survey data. They estimate net doxyPEP use at a median of 4.4 million defined daily doses (DDDs) a year. That is equivalent to 1.9% of Europe's total doxycycline consumption in 2023.

Why It Matters

**This is the other side of the doxyPEP ledger.** Over the past few months the efficacy evidence has stacked up: Australia's national analysis found syphilis **55% lower** after its 2023 guidance ([our coverage](/stories/australia-doxypep-population-impact)), and real-world US clinics report steep drops in chlamydia and syphilis ([our coverage](/stories/doxypep-realworld-nc-australia-gonorrhea-gap)). Regulators weighing broader access, and telehealth and PrEP platforms that want to bundle doxyPEP into subscriptions, now have a first estimate of the antibiotic volume involved. It comes with wide error bars. The CDC's new resistance report already lists drug-resistant gonorrhoea as an **urgent** threat ([our coverage](/stories/cdc-ar-threats-gonorrhea-urgent)), so stewardship questions will follow every expansion. Expect European guideline bodies to ask for exactly this kind of usage data before moving beyond case-by-case prescribing.

How they got there. Sexual-health experts estimated that 33% of PrEP users take doxyPEP, about 24 times a year on average. Both figures carry very wide uncertainty: the 95% credible interval for uptake runs from 5% to 76%, and for frequency from 8 to 54 courses a year. Those inputs went into a Monte Carlo simulation run 10,000 times. The model subtracted a median 326,151 DDDs saved by avoiding chlamydia infections that would otherwise be treated with full doxycycline courses. Syphilis is usually treated with penicillin, so preventing it saves little doxycycline. The researchers instead compared use with syphilis prevalence and estimated about 114 doxyPEP courses for every PrEP user estimated to have syphilis. They did not say whether that ratio is appropriate. The 95% range for the net total is wide: 0.5 million to 18.1 million extra DDDs.

What the authors caution. The figure "should not be interpreted as evidence of doxyPEP contributing to antimicrobial resistance." It is a benchmark for usage, not a measurement of harm. They also note that because the extra antibiotic exposure is concentrated in a relatively small group, selection pressure for resistance in that group could be meaningful even when the Europe-wide share looks modest. Most European guidance so far recommends doxyPEP case by case for people at high risk, especially of syphilis, rather than broad rollout.

Sources

Update — 2026-11-07

Initial entry — story first created.