Sexually transmitted infections (STIs) are among the most prevalent infectious diseases worldwide, posing significant threats to public health and individual well-being. According to the World Health Organization (WHO), more than one million people acquire STIs every day (1). Most STIs are asymptomatic (2). If left untreated, they can lead to severe complications beyond the immediate effects of infection, including neurological and cardiovascular diseases, infertility, ectopic pregnancy, and stillbirths. Moreover, infections such as herpes, gonorrhoeae and syphilis can increase the risk of HIV acquisition (3).

STIs spread mainly through unprotected sexual contact. Men who have sex with men (MSM) remain a key population for STIs due to behaviors, such as unprotected anal sex, multiple sexual partners, casual sex, and group sex (4). Among Chinese MSM, Chlamydia trachomatis, Neisseria gonorrhoeae, and Treponema pallidum are the most commonly reported pathogens. Recent data from Guangdong Province indicated a rising prevalence of Chlamydia trachomatis infection among Chinese MSM, increasing from 13.8% in 2018 to 26.4% in 2022 (5). The prevalence of Neisseria gonorrhoeae infection was about 2.5% (6), while Treponema pallidum infection among MSM continues to be a major public health concern, particularly because of its frequent co-infection with HIV (7).

Current strategies for STIs prevention in China primarily focus on condom promotion and regular testing. Studies have shown that condom promotion programs have achieved moderate success, leading to a notable increase in condom use (8, 9). However, due to the pursuit of sexual pleasure (10), consistent condom use among MSM remains low, thereby limiting its protective effectiveness. Regular testing is a key strategy for identifying STIs, yet the overall STIs testing rate among Chinese MSM remains low. Notably, since syphilis screening is often coupled with HIV testing (such as HIV/syphilis dual test kits), syphilis testing rates among MSM tend to be higher than those for other STIs. Overall, traditional STIs prevention measures remain inadequate to curb the persistent STIs epidemic. In the absence of effective vaccines, researchers and policymakers are actively exploring pharmacological approaches to prevent STIs.

Doxycycline, a broad-spectrum tetracycline antibiotic, is widely recommended for the treatment of chlamydia and syphilis due to its safety, affordability, and minimal drug interactions. In recent years, numerous studies have examined the efficacy of doxycycline prophylaxis in preventing STIs (11, 12). Findings indicated that both daily uptake (doxy-PrEP) and post-exposure intake within 24–72 h after unprotected sexual contact (doxy-PEP) can significantly reduce STIs incidence. Recognizing its preventive potential, the US Centers for Disease Control and Prevention and the British Association for Sexual Health and HIV have issued guidelines recommending doxy-PEP for bacterial STIs prevention among high-risk populations, including MSM (13, 14). Similarly, Germany and Australia have released position statements supporting the prophylactic use of doxycycline for STIs prevention (15, 16).

Despite increasing international evidence supporting doxycycline prophylaxis for STIs prevention, data from China remain limited. Therefore, we conducted a cross-sectional survey among Chinese MSM to assess the current use of doxycycline prophylaxis, aiming to provide evidence for STIs prevention in China.

In this study, 13.4% of participants had used doxycycline prophylaxis for STIs prevention, a proportion lower than those reported in previous studies. A study conducted in Taiwan found that 24.5% of participants had ever used doxy-PrEP (17). In Germany, 23% of participants had used doxycycline for doxy-PEP and 6% for doxy-PrEP (18). A study conducted in the Netherlands reported a similar prevalence of 15% (19). In general, MSM exhibit high willingness but low actual use of doxycycline prophylaxis. Previous studies have shown that more than half of MSM were willing to use doxycycline prophylaxis for STIs prevention (20–22), a proportion substantially higher than the observed utilization proportion. This discrepancy may be due to inadequate awareness of STIs risks and insufficient knowledge regarding doxycycline prophylaxis (21, 23). Additionally, concerns about potential adverse drug effects may deter use. Future efforts should strengthen STIs-related education targeting MSM, improve their knowledge of doxycycline prophylaxis, and promote its timely and appropriate use. This study observed that older participants were less likely to use doxycycline prophylaxis, which may partly contribute to their elevated STIs burden. Evidence from previous studies indicated that older MSM had a higher prevalence of bacterial STIs (24), underscoring the substantial need for targeted prevention within this population. Cultural factors may also play a role. Influenced by traditional norms, older individuals may hold misconceptions or stigmatizing attitudes toward STIs, leading to limited awareness and reduced uptake of doxycycline prophylaxis. These findings highlight the importance of developing tailored interventions targeting older MSM to enhance STIs prevention awareness and promote appropriate use of doxycycline prophylaxis, which could help reduce STIs transmission in this group.

In the present study, a considerable proportion of participants reported engaging in high-risk sexual behaviors, including multiple sexual partners, casual sex, commercial sex, and group sex, indicating a heightened risk of STIs infection. Risk perception serves as a key determinant of preventive behavior. Consistent with this, participants who had casual or commercial sex in the past six months were more likely to use doxycycline prophylaxis for STIs prevention. However, no significant difference in doxycycline use was observed among those reporting multiple sexual partners or group sex, suggesting insufficient recognition of the risks associated with these behaviors. This finding underscores the need for targeted educational interventions to enhance STIs risk awareness and promote evidence-based prevention strategies among MSM. Furthermore, since doxycycline prophylaxis in China can only be obtained through a physician's prescription, limited accessibility may further constrain its uptake. Future research and policy efforts should explore strategies to improve access to doxycycline prophylaxis.

Consistent condom use remains one of the most effective measures for preventing STIs. However, due to limited risk awareness and the pursuit of sexual pleasure, consistent and correct condom use among MSM remains relatively low (25, 26). In this study, only 51.5% of participants reported consistent condoms use during sex, suggesting an elevated risk of STIs transmission. HIV PrEP/PEP, as innovative biomedical prevention approaches, have demonstrated high efficacy in HIV prevention (27, 28). Furthermore, they have been increasingly promoted among MSM in China in recent years (29). In our study, 35.6% of participants reported having used HIV PrEP/PEP, and this group showed a higher prevalence of doxycycline prophylaxis use. This association may reflect stronger health awareness and greater preventive motivation among individuals who engage in HIV PrEP/PEP. Alternatively, evidence suggested that HIV PrEP/PEP use may lead to increased high-risk sexual behaviors among MSM, thereby raising their STIs risk and driving demand for additional preventive measures such as doxycycline prophylaxis (30, 31). Unlike HIV PrEP/PEP, doxycycline is an antibiotic and poses potential risks of antimicrobial resistance (32). Evidence has shown that doxy-PEP may promote not only tetracycline resistance but also cross-resistance to other antimicrobial agents (33). From a public health perspective, doxycycline prophylaxis may not be suitable for large-scale implementation and should be administered in a selective and targeted manner (34). Its implementation should be accompanied by antimicrobial stewardship and continuous surveillance of resistance patterns.

This study has several limitations. First, as a cross-sectional survey, the findings can only identify factors associated with doxycycline prophylaxis use among MSM, and cannot establish causal relationships. Second, participants were recruited through convenience sampling, which may limit the representativeness of the sample. Thus, the generalizability of the findings should be interpreted with caution. Future studies should adopt random sampling strategies to enhance external validity. Third, as data were collected through an online questionnaire, potential privacy concerns and stigma may have introduced social desirability bias.

Doxycycline prophylaxis utilization among MSM in China remains at a relatively low level. Older MSM reported a lower usage proportion, whereas individuals engaging in casual or commercial sex were more likely to use doxycycline prophylaxis. These patterns may reflect inadequate awareness of STIs risks, insufficient knowledge of doxycycline prophylaxis, and restricted accessibility in China. Targeted educational interventions are urgently needed to enhance STIs prevention awareness among MSM. Besides, future research could integrate qualitative insights to explore barriers and facilitators of doxycycline use, developing more effective and acceptable STIs prevention strategies.