Science and Tech


Drug shows promise in preventing sexually transmitted infections

The antibiotic doxycycline is traditionally used to treat things like malaria and acne, but a new study shows it could be used to prevent STIs.
Posted at 2:48 PM, Jun 09, 2023

Some women who have unprotected sex and are worried about getting pregnant take the Plan B pill to prevent that from happening. Not everyone agrees with its use, but research shows it is 89% effective if taken within 72 hours after sex.

A new study shows another drug works similarly, in the sense that if it's taken within three days after unprotected sex, it can reduce the chances of getting a sexually transmitted infection (STI) — like chlamydia, gonorrhea or syphilis — by 65%.

The drug is called doxycycline. It's not a new drug, as it's historically been used to treat things like anthrax exposure, malaria and acne. But a new study shows it could be used to prevent STIs if taken before a diagnosis.

Dr. Annie Luetkemeyer is the infectious disease physician who pioneered the study, and she believes the drug could change the way sexually active individuals protect themselves.

"What we're doing isn't working," she said. "So I think we need new tools and awareness so we can do a better job controlling sexually transmitted infections."

The study comes as rates of chlamydia, gonorrhea and syphilis have continued to increase in the U.S. in recent years.

The condom display at Chimes pharmacy in Berkeley, Calif

Why are sexually transmitted infections on the rise?

The CDC made headlines this fall after warning cases of some sexually transmitted infections are at their highest levels in decades.


Traditionally, most people only get treated for STIs if they notice symptoms, but this new method gets out ahead of the infection so the body can prevent it from occurring. In medical terms, it's known as post-exposure prophylaxis (PEP).

It's important to note that the study only examined men who had sex with other men, for whom STIs spread more rapidly than in other populations. It's unclear how the drug might work for heterosexual couples.

However, other physicians, like Dr. Kara Alexandrovic, say it shows promise as a new way to treat STIs.

"It's really exciting for certain populations right now," she said. "And for a more widespread population, it's just exciting to think about future directions."

The study showed 2% of participants stopped taking doxycycline due to side effects like rashes and sun sensitivity. It is currently a prescription medication that is not available over-the-counter.