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Doxycycline as Prep for STI

Jun 16, 2017

Hi Damon,

Sometimes ago, I heard that several studies were conducted in order to determine if Doxycycline could be used as Prep for bacterial STIs. Any development on that? What is also your view on the subject, especially regarding the development of resistant bacteria.

Thank you

Response from Mr. Jacobs

Hi there,

Yes, as you recently heard, A small pilot study conducted with HIV-positive men who have sex with men in 2015 found evidence that a daily dose of the antibiotic doxycycline provides a protective effect against three sexually transmitted infections (STIs). The results of the study show promise that doxycycline could be used as medication-based chemoprophylaxis for chlamydia, gonorrhea and syphilis (

A second trial was then conducted in 2016 with HIV-negative men which showed significant decreases in incidence for both syphilis and chlamydia, but not gonorrhea. (

So with this information, I asked a doctor in New York City if she thought doxycycline as prevention would work for me, and other sexually active individuals who were having sex without condoms and at potential risk of getting an STI. Her recommendation was no, as there is still a lot that is unknown about this drug, including how easily one can build resistance to it. Given that were are quickly running out of medications to cure syphilis, chlamydia, and gonorrhea, she (and others I asked) believed it is better to err on the side of caution for now, and use doxycycline for treatment after a diagnosed STI, not before.

My personal hope is that consumers do have the option to use doxycycline as Pre-exposure prophylaxis in the future, instead of waiting until after a diagnosed infection has taken place. In many areas of the U.S., if you believe you have been exposed to chlamydia you will be given doxycycline instead of waiting for the results of a test, and some people I know are using doxycycline as a prophylactic in this regard (meaning they go in and ask for it instead of waiting to be told they need it). But this strategy still involves treating exposure after the fact, not prior. Clearly, there is need and demand for people to have a way to be proactive instead of reactive about exposure to STIs.

It seems that medically this is still a new area, and more time and research is needed before there is consensus. I hope that you and every person is able to consider the risks/benefits before using a strategy that is still largely experimental, and whose consequences are unknown.

Does PrEP protect only against one strain of HIV?
Prep, Oral Sex, Recently Seroconverted Partner

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