A daily pill to prevent STIs? It may work, scientists say

A photo provided by the National Institute of Allergy and Infectious Diseases shows doses of doxycycline, a widely used antibiotic. (National Institute of Allergy and Infectious Diseases via The New York Times) — NO SALES; EDITORIAL USE ONLY—
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A daily dose of a widely used antibiotic can prevent some infections with syphilis, gonorrhea and chlamydia, potentially a new solution to the escalating crisis of sexually transmitted infections, scientists reported Thursday.

Their study was small and must be confirmed by more research. Scientists still have to resolve significant questions, including whether STIs might become resistant to the antibiotic and what effect it could have on healthy gut bacteria in people taking it every day.

The approach would be recommended primarily to people at elevated risk of STIs during certain periods, said Dr. Jeffrey Klausner, an infectious diseases physician at the University of Southern California who was not involved in the new work.

“In general, the more choices we have for people, the more prevention options we have, the better,” he said.

Previous studies have shown that the antibiotic doxycycline substantially cuts the risk of new infections if taken within 72 hours after unprotected sex. The Centers for Disease Control and Prevention now recommends taking doxycycline after “oral, vaginal or anal sex.”

The recommendation applies only to gay and bisexual men and transgender women who have had an STI within the previous year or who may be at risk for one. There is not enough evidence that the strategy, called doxy-PEP, works for other groups, the agency concluded.

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