A ‘Morning-After Pill’ for Sexually Transmitted Infections Is Almost Here

Medicine may be about to achieve a long-sought goal: a “morning-after pill” to prevent sexually transmitted infections. It could sharply reduce soaring rates of illness and huge health care costs.

The effectiveness of this pill—and it literally is a pill, a 200-milligram tablet of the antibiotic doxycycline—has been studied for a decade, and people have taken it covertly for years. But study results published in The New England Journal of Medicine look likely to tip the pill into clinical practice. In the study, conducted in San Francisco and Seattle, participants who took a single dose within 72 hours of having sex without a condom were only a third as likely to contract chlamydia, gonorrhea, or syphilis as those who didn’t take the pills.

As with everything in medicine, there are footnotes to the findings, and risks to balance the benefits. The study was conducted only among gay and bisexual men, along with transgender women and nonbinary people assigned male at birth. Within those groups, it was limited to people who had been diagnosed with a sexually transmitted…