Study: Prophylactic Use of Doxycycline Did Not Lower Incidence of Chlamydia, Gonorrhea in Cisgender Women


The results have been highly anticipated, following other studies showing that doxycycline increased protection against sexually transmitted infections for cisgender men and transgender women.

The prophylactic use of low dosage doxycycline did not significantly lower the incidence of sexually transmitted infections (STIs) among cisgender women, according to results of a study published in The New England Journal of Medicine.1,2 According to a press release, the results of the dPEP-KE study have been highly anticipated, following other studies that showed doxycycline resulted in significant levels of protection against STIs for cisgender men and transgender women.1

Doxycycline white medical pills and tablets spilling out of a drug bottle. | Image Credit: luchschenF -

luchschenF -

“Doxycycline [post-exposure prophylaxis (PEP)] needs to be studied further among [those] assigned female sex at birth. I am hopeful that it will work for everyone regardless of sex and gender, but in our study many women didn’t take the doxycycline they were given. We need STI prevention that is proven, accessible, and easy to use,” Jenell Stewart, DO, MPH, the dPEP Kenya study director and infectious disease physician at Hennepin Healthcare and the University of Minnesota, said in the press release.1

The study was conducted by investigators from the University of Washington, Kenya Medical Research Institute, and Hennepin Healthcare Research Institute, and it was the first study to include cisgender women, according to the press release. Investigators used hair samples to measure doxycycline in the system, which showed that the use of the drug as PEP was low.1

Investigators enrolled 449 cisgender women who were taking daily oral HIV pre-exposure prophylaxis at a single site in Kisumu, Kenya, according to the press release. The individuals were randomly given doxycycline or the standard of care. At the study entry, 18% of individuals had and STI, with the rate of STIs remaining high among the study duration. There were 109 new STIs diagnosed, with 50 among those who were using doxycycline over the 12-month follow-up period.1

About The dPEP-KE Study

Title: Doxycycline PEP for Prevention of Sexually Transmitted Infections Among Kenyan Women Using HIV PrEP (dPEP-KE)

Clinicaltrials.Gov ID: NCT04050540

Sponsor: University of Washington

Completion Date: October 2022

Approximately 78% of the STI diagnoses were chlamydia, including 35 patients who were taking doxycycline and 50 who were in the standard-of-care group. There was only 1 case of syphilis, according to the press release, so investigators could not determine the impact of PEP on preventing syphilis among the patient population.1

In the initial results, investigators reported that they had not established a reason for why doxycycline did not prevent bacterial STIs, such as chlamydia and gonorrhea. However, in the published study, the investigators stated that antibiotic resistance could be a reason why gonorrhea was not prevented, with a high rate of doxycycline-resistant gonorrhea. The results did not show any cases of antibiotic resistant chlamydia.1

“The results from the study are deeply disappointing, and we are committed to understanding why doxycycline PEP wasn’t taken. We are actively working to find ways to support adherence that will work for and can be used by women,” Elizabeth Bukusi, PhD, MPH, a senior principal clinical research scientist at the Kenya Medical Research Institute and professor at University of Washington in Departments of Global Health and Ob/Gyn, said in the statement.1


  1. Doxycycline prophylaxis use low and did not prevent STIs among cisgender women. News release. Hennepin Healthcare Research institute. December 21, 2023. Accessed January 3, 2024.
  2. Stewart J, Oware K, Donnell D, Violette LR, et al. Doxycycline Prophylaxis to Prevent Sexually Transmitted Infections in Women. N Engl J Med. 2023;389(25):2331-2340. doi:10.1056/NEJMoa2304007
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