Feb 22, 2024 1:00 pm ET
Community-Based Research Centre (CBRC) CATIE

Doxy-PEP and doxy-PrEP: Pills to prevent syphilis

Presented in partnership with Community-Based Research Centre (CBRC).

Syphilis rates have been on the rise in Canada since the early 2000s, disproportionately affecting gay, bisexual and other men who have sex with men (gbMSM). In the last few years, syphilis cases have increased even more dramatically through heterosexual transmission, which has led to more infants being born with syphilis and more stillbirths.

Given these ongoing and escalating crises, there is an urgent need for new approaches to syphilis prevention. Enter doxy-PEP and doxy-PrEP: two possible off-label uses of an antibiotic to prevent some bacterial sexually transmitted infections such as syphilis. Doxy-PEP (doxycycline post-exposure prophylaxis) can be taken after a possible exposure to syphilis, while doxy-PrEP (doxycycline pre-exposure prophylaxis) is to be taken on an ongoing basis before and after exposure to prevent transmission. Two large studies have shown that doxy-PEP is effective at preventing syphilis among gbMSM and trans women, and a similar study of doxy-PrEP is currently underway. However, concerns have been raised around the impact of doxy-PEP and doxy-PrEP on antimicrobial resistance, which has been explored in ongoing research. 

This third webinar in a series on syphilis in Canada reviews how doxy-PEP and doxy-PrEP are currently being used to prevent syphilis, as well as explores the concerns around their use and the evidence for their efficacy. A panel discusses what is needed to mitigate risks and implement doxy-prophylaxis as a system-level strategy, while also considering the implications for service providers, health systems and communities most affected by syphilis.

Moderator: Shriya Hari, CATIE


  • Troy Grennan, MD, BC Centre for Disease Control; University of British Columbia 
  • Jaris Swidrovich, PharmD, University of Toronto 
  • Aaron Clarke, AIDS Committee of Toronto  
  • Jordan Upshaw, AIDS Coalition of Nova Scotia 
  • Kevin Woodward, HQ; McMaster University