Study shows doxyPEP’s diminished effectiveness against gonorrhea
As a gay man this saddens me but as a biologist I feel somewhat vindicated in what I’ve been saying all along, prophylactic use of antibiotics has led to rapid resistance. Fortunately it still works very well for chlamydia and syphilis, close to 90% reduction for both but gonorrhea has rapidly developed resistance to tetracycline antibiotics to the point where it’s apparently having little effect on preventing gonorrhea infection where DoxyPEP is widely used.
So watch out boys, you might not be as protected as you think, though it was only ever mildly effective against gonorrhea, something like 55%. But at least it seems to be more effective against chlamydia and syphilis than originally thought.
From the article:
US research also suggests that increases in tetracycline-resistant gonorrhea strains may be linked to rising use of doxyPEP. A 2025 study by researchers at the University of Washington found that, among gonorrhea isolates collected at a sexual health clinic in Seattle, where the strategy was implemented in June 2023, the prevalence of tetracycline-resistance genes rose from 27% in 2017 to 70% by the middle of 2024.
In a July 2025 letter to the New England Journal of Medicine, researchers reported that the presence of the tetM gene, which confers high-level tetracycline resistance, in US gonorrhea samples rose from less than 10% in 2020 to 30% in the first quarter of 2024. The highest prevalence of gonorrhea isolates carrying tetM genes was found in the Pacific Northwest.