Dermatological adverse effects of doxycycline as post-exposure prophylaxis for sexually transmitted infections among men who have sex with men: real-world findings from a multicentre study

Objectives Doxycycline has demonstrated a favourable safety profile in clinical trials of post-exposure prophylaxis (doxy-PEP) for sexually transmitted infections; however, potential adverse effects may limit its feasibility. We aimed to investigate dermatological adverse effects of doxy-PEP in real-world settings. Methods This multicentre retrospective cohort study was conducted between October 2023 and February 2025, following the implementation of doxy-PEP among MSM. Individuals were encouraged to report adverse effects after initiating doxy-PEP. Data on medical history, previous therapeutic doxycycline exposure and history of allergic reactions were collected from electronic medical records. Results A total of 671 MSM were included, comprising 460 people with HIV and 211 on pre-exposure prophylaxis. Among them, nine individuals (1.3%) developed skin reactions, with an incidence rate of 1.0 per 100 person-years. Most were fixed drug eruptions (n = 8), with one case of photosensitivity. These reactions typically appeared within 24 h of exposure; and all nine individuals discontinued doxy-PEP, and symptoms resolved within 1–3 weeks. Individuals with a prior history of allergic reactions to any medication were at greater risk of experiencing adverse skin reactions (odds ratio, 6.99; 95% CI, 1.83–26.65). Notably, all individuals who experienced dermatological adverse events had previously used therapeutic doxycycline, though only three reported prior allergic reactions to it. Conclusions Although dermatological adverse events associated with doxy-PEP were generally mild, they led to discontinuations. These findings underscore the importance of obtaining a thorough history of drug allergy before initiating doxy-PEP and highlight the need for vigilant monitoring of dermatological adverse events during its use.