The Centers for Disease Control and Prevention (CDC) proposed a new guideline this week for high-risk patients to take the antibiotic known as doxycycline as a morning-after pill to decrease the risk of sexually transmitted infections (STIs).
Experts say health officials will likely endorse the guideline, which was published on Monday in the Federal Register.
The public has 45 days to comment on the proposal.
The CDC's guideline is based on previous studies that show a "demonstrated benefit" in specifically reducing chlamydia, gonorrhea, and syphilis infections after people took a single 200 milligram doxycycline pill no later than 72 hours after unprotected sex.
The CDC originally concluded in its previous 2021 sexually transmitted infection treatment guidelines that more research was needed regarding whether doxycycline was effective at preventing sexually transmitted infections.
Several recent randomized trials, however, showed that when high-risk patients took doxycycline within three days of unprotected sex, they were significantly less likely to get chlamydia, syphilis or gonorrhea — compared with people who did not take the pills after sex.
The studies focused on gay and bisexual men as well as transgender women at higher risk to contract a sexually transmitted infection.
One of the most prominent of these recent studies was published in The New England Journal of Medicine earlier this year.
It showed a two-thirds decrease in the incidence of syphilis, gonorrhea and chlamydia among study participants, all of whom had a sexually transmitted infection within the previous year.
Currently, there is not enough evidence that the strategy will also benefit heterosexual men and women.
The CDC emphasized in the proposed guideline that the antibiotic is indicated only for gay, bisexual men and transgender women.
"This preventative medication will certainly provide some benefit against the increasing STD rates that we are seeing in this country," Dr. Aaron Glatt, chief of infectious diseases at Mount Sinai South Nassau Hospital in Long Island, New York, told Fox News Digital.
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"However, it doesn’t do anything to address the high-risk behaviors that people are engaging in," he cautioned.
"There is a concern that such preventive therapies will make people comfortable in engaging in high-risk behavior, thinking that they will be protected."
Sexually transmitted infections have increased by 42% from 2011 to 2021, with more than 2.5 million cases of chlamydia, gonorrhea, and syphilis reported in 2021, according to the CDC.
In 2021, gonorrhea rates increased more than 4%, syphilis rates rose by approximately 32% for combined stages of the infection, and chlamydia rates increased nearly 4%.
A specific type of syphilis that infants get at birth known as congenital syphilis increased by more the 203% in the past five years, the CDC added.
Doxycycline is a common antibiotic often prescribed to treat acne, prevent Lyme disease and prevent malaria.
It is also the drug of choice to treat Chlamydia trachomatis, the bacteria that causes the sexually transmitted infection known as chlamydia.
Although penicillin is the drug of choice to treat Treponema pallidum, the causative agent of syphilis, many health care providers are currently using doxycycline as an alternative to treat the infection because of the national shortage of penicillin.
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The antibiotic can make patients more sun-sensitive, so doctors always encourage patients to wear sunscreen when taking the medication.
It also can cause erosions and ulcers in the esophagus, so patients are encouraged to take the medication at least one hour before going to bed.
Doxycycline is a cheap antibiotic that has been available for more than 40 years, according to the Associated Press.
A year ago, San Francisco's health department began promoting doxycycline as a morning-after prevention measure, the AP also reported.
