An STI 'morning-after' pill? What you need to know about DoxyPEP — and who can get it

Doctors working to limit the spread of syphilis, chlamydia and gonorrhea — and their potential complications if left untreated — are turning to a promising new means of prevention. 

It's known as DoxyPEP, which stands for doxycycline (an antibiotic) post-exposure prophylaxis. 

Some liken it to a "morning-after pill," as you take it after sexual activity that may have left you at risk of contracting an STI.

For Dustin Hutton-Alcorn, a 33-year-old gay man in Abbotsford, B.C., having DoxyPEP on hand offers him some peace of mind that he has an additional means of protecting his sexual health. 

"[It] allows me to be a responsible adult, especially in the queer community," he told CBC News.

The efficacy of DoxyPEP was studied in people at elevated risk for STIs: two-spirit, gay, bisexual, and queer cisgender men and transgender women. The small but growing number of studies showed it significantly reduced the risk of contracting syphilis, chlamydia and — to a lesser extent — gonorrhea among those groups.

But access to DoxyPEP is limited, depending on where you live, and it's not a federally approved treatment, which may create further barriers to availability and awareness. 

Doxycycline is a commonly used antibiotic that health-care providers may prescribe to treat some bacterial infections — including syphilis and chlamydia — as well as conditions like acne and rosacea and to prevent malaria. It has minimal potential side effects, including stomach upset and sensitivity to sun. 

DoxyPEP is similar to a method of HIV prevention known as PrEP (pre-exposure prophylaxis) that sees 2SGBTQ+ people at risk of contracting HIV take a daily dose of an anti-retroviral medication.

PrEP has proven to be highly effective in reducing the risk of getting HIV from sexual activity, when taken as prescribed, virtually eliminating the risk of contracting the virus that causes AIDS. 

DoxyPEP's 200-milligram dose is best taken within 24 hours, but no later than 72 hours after condomless oral or anal sex.

There is compelling evidence that it's effective in preventing sexually transmitted bacterial infections, said Dr. Peter Phillips, an infectious diseases specialist and member of the DoxyPEP program at the B.C. Centre for Excellence in HIV/AIDS (BC-CfE). 

Three randomized controlled studies have shown that doxycycline taken post-exposure can reduce the risk of being infected with syphilis and chlamydia by more than 70 per cent, Phillips said. That includes one conducted in California, the first jurisdiction in North America to implement guidelines on DoxyPEP. 

It was less successful in preventing gonorrhea infections, but still reduced the risk by about 50 per cent, he said.