An orally consumable antibiotic called doxycycline can reduce sexually transmitted infections (STIs) by two-thirds in both the cases of gay sex and transgender women having unprotected sex given they take the medication within 72 hours of the intercourse, a new study found.

The findings, published in the New England Journal Of Medicine, noted that the combined incidences of gonorrhea, chlamydia and syphilis were cut by two-thirds in persons who were taking doxycycline post-exposure prophylaxis (doxy-PEP).

"Effective methods for preventing sexually transmitted infections are badly needed," Hugh Auchincloss, M.D., National Institute of Allergy and Infectious Diseases (NIAID) told Medical Express. "This is an encouraging finding that could help reduce the number of sexually transmitted infections in populations most at-risk."

The study also pointed toward a slight increase in anti-bacterial resistance, but further research is required to determine it.

More than 110 million incidents of sexually transmitted infections among men and women in the U.S. were reported in 2008, among which about 22 million were in young men and women aged between 15-24 years, as per estimates by the Centers for Disease Control and Prevention (CDC).

In 2021, an estimated 2.5 million people reported syphilis, gonorrhea and chlamydia, up from 2.4 million cases in 2020, as per the CDC.

The latest study, led by researchers from the University of California at San Francisco (UCSF) and the University of Washington, Seattle, involved 501 adults. All of them were assigned male sex at birth and had sex with a man in a given year. Researchers reviewed factors like HIV diagnosis or if the participants were planning to take pre-exposure prophylaxis (PrEP) medication to prevent HIV acquisition or if they had an onset of gonorrhea, chlamydia or early syphilis before. After these assessments, it was found that 327 participants were taking HIV PrEP medications and 174 of them were living with HIV.

As part of the study, some of them were given doxy-PEP of a 200 mg prescribed dose within 24 hours but no later than 72 hours after unprotected sex. After a number of trials and medical assessments, research doubled down on the efficacy of the medication in weeding out STIs.

"Given its demonstrated efficacy in several trials, doxy-PEP should be considered as part of a sexual health package for men who have sex with men and transwomen if they have an increased risk of STIs," Annie Luetkemeyer, M.D., professor of infectious diseases at Zuckerberg San Francisco General Hospital at UCSF, and co-principal investigator of the study, told Medical Express.

"It will be important to monitor the impact of doxy-PEP on antimicrobial resistance patterns over time and weigh this against the demonstrated benefit of reduced STIs and associated decreased antibiotic use for STI treatment in men at elevated risk for recurrent STIs," Luetkemeyer added.

STI Prevalence
Data collected by Superdrug Online Doctor shows the prevalence of STDs across space and time. Photo courtesy of Shutterstock