Doxycycline Prophylaxis Taken Within 72 Hrs Cuts Gonorrhea, Chlamydia, and Syphilis Risk by Two Thirds in Trans Women and MSM

A cheap and widely accessible medication finds new application in a promising strategy to fight against sexually transmitted infections (STIs). Long after it was first shown to be effective, more evidence has revealed that doxycycline post-exposure prophylaxis (doxyPEP) is on the verge of becoming common practice.


Doxycycline Credit: SFAF

DoxyPEP is a strategy designed to prevent STIs in people who have just had sex without protection. It involves taking 200mg of doxycycline by mouth within 3 days of having unprotected sexual intercourse. Some people call it the “morning after”pill for STIs.

Read Also: Do You Lack Self-Control When It Comes to Sex? A Science-Backed Sex Addict’s Guide to Dodging STDs

The United States’ national public health agency, Centers for Disease Control and Prevention (CDC), sent out a tentative memo saying how doxycycline should be used to prevent STIs. This happened just recently on the 2nd of October, and the recommendations will influence the use of doxyPEP in the States and other countries too.

 DoxyPEP is effective for transgender people and MSM

The strategy has been proven to be effective for men who have sex with men (MSM) and transgender women. If they use doxycycline in this manner, it protects them against chlamydia, syphilis, and gonorrhea infections. The results of studies that have been done provide strong support for this suggestion.

However, there is proof that doxyPEP is not very beneficial for cisgender women. This could probably be due to several factors, like non-compliance with medications, lack of awareness of the risk of STIs, more antibiotic resistance in some areas compared to others, fewer sexual partners, which in turn leads to not taking the drug, and many more.

A clinical trial carried out by Dr. Annie Luetkemeyer and her colleagues in San Francisco and Seattle showed how the drug effectively reduces STIs in MSM and trans women. They are very confident about the outcome of the trial, which involved 501 participants who were on pre-exposure prophylaxis against HIV infection and who had gonorrhea, syphilis, or chlamydia infection over the past year.

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Results revealed that the rate of infection was greatly reduced by two-thirds in the participants after doxyPEP was taken after sex without a condom. The incidence of gonorrhea, including pharyngitis gonorrhea, was lowered by 55%. Also, doxyPEP was effective in 88% of the participants on PrEP compared to the control, which yielded just 74%. The rate at which syphilis occurred was reduced, even though the total incidence before the trial was low.

These findings demonstrated the efficacy of doxy-PEP among MSM in a socioeconomically and racially diverse population, irrespective of HIV status.

Clinical significance

These results yield promise and hope for those at risk, especially persons who continuously suffer from STIs. MSM and trans women have a chance at a better quality of life.

However, scientists are concerned that resistance could build against doxycycline. Already, gonorrhea is resistant to some antibiotics.

If this resistance develops and spreads globally, it could make the drug significantly ineffective even against other infections.

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DoxyPEP has been shown to be potent against the most prevalent STIs in MSM and trans women, and this new public health strategy could significantly reduce the incidence of STIs in the long run. However, so far, it hasn’t been proven to be effective for cisgender women.


Luetkemeyer, A. F., Donnell, D., Dombrowski, J. C., Cohen, S., Grabow, C., Brown, C., Malinski, C., Perkins, R., Nasser, M., López, C. B., Vittinghoff, E., Buchbinder, S., Scott, H., Charlebois, E. D., Havlir, D. V., Soge, O. O., &Celum, C. (2023). Postexposure doxycycline to prevent bacterial sexually transmitted infections. The New England Journal of Medicine, 388(14), 1296–1306.


Doxycycline Post-Exposure Prophylaxis reduces the risk of catching gonorhea chalamidy and syphilis by two thirds in Trans Women and MSM



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