CDC offers guidance on doxycycline for postexposure STI prophylaxis

Doxycycline postexposure prophylaxis can reduce syphilis, chlamydia, and gonorrhea in at-risk populations and may offer a new approach to preventing sexually transmitted infections (STIs), according to new guidelines.

The CDC offered new recommendations on providing doxycycline postexposure prophylaxis (doxy PEP) as a patient-managed biomedical prevention strategy against sexually transmitted infections (STIs) in those at high risk, including transgender women and men who have sex with men (MSM).

The regimen is targeted specifically to syphilis, chlamydia, and gonorrhea, which have increased in the U.S. and disproportionately affect people who are gay, bisexual, MSM, and transgender women, the CDC said. Three large randomized controlled trials showed that 200 mg of doxycycline taken within 72 hours after sex reduced syphilis and chlamydia infections by more than 70% and gonococcal infections by approximately 50%, the guidelines noted. No serious adverse events have been associated with use of doxy PEP, but there are no data on the effects of long-term intermittent use of the drug on resistance and the microbiome, the agency said. The guidelines were published June 6 by MMWR.

The recommended dose of doxy PEP is 200 mg, and patients should not exceed a maximum dose of 200 mg every 24 hours, the CDC said. The CDC recommends that clinicians counsel patients who are gay, bisexual, MSM, or transgender women and have a history of at least one bacterial STI in the past 12 months about the benefits and harms of doxy PEP. The regimen could be discussed using a shared decision-making approach with MSM and transgender women who have not had a bacterial STI diagnosed during the previous year but will be participating in sexual activities known to increase STI exposure. After shared decision-making talks, clinicians can offer patients a prescription for doxy PEP to be self-administered within 72 hours after oral, vaginal, or anal sex.

Doxy PEP should be offered as part of a comprehensive sexual health approach, including risk reduction counseling, STI screening and treatment, recommended vaccination, and access to HIV pre-exposure prophylaxis, HIV care, or other services as appropriate, the CDC said. Patients receiving doxy PEP should undergo bacterial STI testing at anatomic sites of exposure at baseline and then every three to six months. Ongoing need for doxy PEP should be assessed at the same intervals. HIV screening should be performed according to current recommendations.

"Because of increasing rates of bacterial STIs and the reported high efficacy for the reduction of STIs in the reviewed clinical trials, the potential benefits of doxy PEP are notable," the guidelines stated. "Systematic reviews of potential harms appear low in the short-term and unknown but potentially concerning in the long-term. Overall, the intervention appears feasible and acceptable and will require a focused effort for equitable implementation."