‘Morning-After Pill’ for STIs Gets Green Light From U.S. Health Officials for Gay and Bisexual Men

Health officials are endorsing a common antibiotic as a new “morning-after” treatment to prevent STIs in gay and bisexual men and transgender women.

Studies indicate that those who took doxycycline within three days of engaging in unprotected sex (a strategy also known as doxy-PEP) were much less likely to become infected with chlamydia, gonorrhea, and syphilis than those who do not take the antibiotic after sex. A guideline for doxycycline’s usage to combat STIs was released Monday by the Centers for Disease Control and Prevention (CDC), and officials are moving to finalize it after a 45-day public comment period.

“More tools are desperately needed” to combat the rising spread of STIs, according to the CDC’s Jonathan Mermin, which accounts for the speedy proposal and approval process. The Centers’ guideline is based on four separate studies which showed that doxycycline proved massively effective in preventing the resurgence of STIs in gay men, bisexual men, and transgender women who had contracted an STI in the previous 12 months.

One of the studies, published earlier this year in The New England Journal of Medicine, found that gay and bisexual men and transgender women previously diagnosed with an STI who took doxycycline pills were far less likely to experience a recurrence than those who did not take the antibiotic. Of those who did, 90 percent were less likely to contract chlamydia, 80 percent were less likely to contract syphilis, and 50 percent were less likely to contract gonorrhea.

Right now, there isn't much evidence indicating doxycycline has a similar effect in treating STIs in heterosexual men and women. However, the CDC maintains that statistic could change as more testing is conducted. STIs in the United States reached record highs for the eighth straight year in 2023.

Doxycycline has been commonly available for almost 50 years. It’s already used to prevent the growth of bacteria, and treats a variety of ailments such as acne, eye infections, and gum disease. Side effects include stomach irritation, and the chance of sun rash. Researchers plan to continue monitoring to see if more widespread use of doxy-PEP leads to increased rates of antibiotic-resistant infections; some previous studies have not shown a significant increase.