CDC advises using an antibiotic as a “morning after pill” against sexually transmitted diseases

Some people should consider taking an antibiotic as the morning-after pill to try to prevent certain sexually transmitted diseases, U.S. health officials recommended Tuesday.

The Centers for Disease Control and Prevention (CDC) ended its recommendation to take doxycycline after unprotected sex to prevent chlamydia, gonorrhea, or syphilis infections.

CDC officials consider this the first new sexually transmitted infection prevention tool in decades, and say the innovation is much needed. Rates of syphilis, chlamydia and gonorrhea have been increasing for years, especially in gay and bisexual men, although the latest data suggests that cases of chlamydia and gonorrhea stopped increasing in 2022.

The new guideline is specific to gay and bisexual men and transgender women who had a sexually transmitted disease in the previous year and are at high risk of being reinfected. Studies have shown that doxycycline works in that group, but there is not enough evidence to make the same recommendation for other people, agency officials said.

Authorities call the doxy treatment PEP, short for doxycycline post-exposure prophylaxis. Doctors can prescribe a 200-milligram dose of doxycycline to be taken within three days of unprotected sex, according to the CDC.

In October, the CDC released a draft version of the guidelines. The proposed text was slightly modified following a public comment period. The changes include clarifying that the pills should only be taken once every 24 hours and that doctors should reevaluate the regimen with patients every three to six months.