Associations between antibacterial mouthwash use with sexual behaviours and sexually transmitted infections among Chinese men who have sex with men: a cross-sectional study

Background. Mouthwash is a commonly used product with the potential to prevent STIs. This study aimed to determine the association between mouthwash use frequency with sexual behaviours and STIs among Chinese men who have sex with men (MSM). Methods. A cross-sectional study was conducted among MSM in Xi'an, China, from January to September 2022. Participants were categorised into non-mouthwash users, occasional (used it less than once every week) and frequent (used it more than once every week) mouthwash users. Multinomial logistic regression was performed to identify the association between mouthwash use frequency with sexual behaviours. Results. Of 838 MSM included in the analysis, 621 (74.11%) reported never using mouthwash, whereas 47 (5.60%) used it occasionally and 170 (20.29%) used it frequently. Frequent mouthwash users had a lower prevalence of chlamydia compared with occasional users (8.33% vs 23.93%, P < 0.05). In comparison with participants who consistently used condoms, those who used condoms occasionally and never used condoms were 1.8 (adjusted odds ratio (aOR) 1.838, 95% confidence interval (CI) 1.011-3.375) and 4.5 (aOR 4.538, 95% CI 1.259-16.362) times more likely to be frequent mouthwash users, respectively. Participants with more sexual partners who engaged in kissing (aOR 1.060, 95% CI 1.019-1.103), receptive oral sex (aOR 1.065, 95% CI 1.024-1.108), insertive oral sex (aOR 1.043, 95% CI 1.014-1.072) and receptive anal sex (aOR 1.076, 95% CI 1.027-1.127) were more likely to be frequent mouthwash users. Conclusion. MSM with more sexual partners or lower condom use frequency were more likely to be frequent mouthwash users. However, frequent mouthwash users had a lower chlamydia prevalence.