Doxycycline postexposure prophylaxis (doxyPEP) is prescribed to prevent certain sexually transmitted bacterial infections in people at increased risk.
Common bacterial sexually transmitted infections (STIs) include chlamydia, gonorrhea, and syphilis. In 2022, more than 1.6 million cases of chlamydia, 648 056 cases of gonorrhea, and 207 555 cases of syphilis were reported in the US. Chlamydia, gonorrhea, and syphilis disproportionally affect gay men, bisexual men, other men who have sex with men, and transgender women.
Chlamydia, gonorrhea, and syphilis often do not produce any symptoms, but they can result in serious complications. Chlamydia and gonorrhea can cause infertility. Syphilis can cause skin rashes, decreased vision and hearing, muscle weakness, heart failure, and dementia, and if transmitted during pregnancy, it may result in congenital syphilis, which can cause developmental delays, seizures, rash, and bone and joint abnormalities in affected infants.
Doxycycline is a commonly used antibiotic that treats many bacterial infections, including chlamydia, gonorrhea, and syphilis. It is a safe and well-tolerated medication but should not be used during pregnancy. The most common side effects are nausea, diarrhea, inflammation of the esophagus, and sun sensitivity.
Postexposure prophylaxis (PEP) refers to taking a medication to prevent infection after a known or possible exposure to an infection.
DoxyPEP involves taking a single 200-mg dose of doxycycline within 72 hours of oral, vaginal, or anal sex to prevent bacterial STIs. No more than 1 dose (200 mg) within 24 hours is recommended. When taken as prescribed, this regimen has been shown to reduce the risk of chlamydia and syphilis infections by more than 70% and gonorrhea infections by about 50%.
People who should consider taking doxyPEP include those assigned male sex at birth (including cisgender men and transgender women) who are gay, bisexual, or otherwise have sex with men and have had a bacterial STI in the last 12 months. People assigned female sex at birth, heterosexual men, and transgender men may also benefit, but studies are limited. Therefore, these groups are not included in current doxyPEP treatment recommendations. However, patients at high risk of bacterial STIs or who have had a bacterial STI within the last 12 months could consider doxyPEP based on its overall benefits and risks, including side effects of the medication and concern for development of bacterial resistance.
DoxyPEP should be used as part of a comprehensive sexual health approach, including other ways to reduce risk of STIs, such as reducing number of sex partners, using condoms, and getting tested regularly. People who are prescribed doxyPEP should undergo bacterial STI testing at all anatomical sites (eg, oral, vaginal, or anal) of sexual exposure at baseline and every 3 to 6 months thereafter. HIV screening should also be performed for individuals who are HIV-negative or whose HIV status is unknown.