ObjectiveTo understand the status of synthetic drug use， high-risk sexual behavior and associated factors among men who have sex with men （MSM） in Shanghai.

MethodsMSM subjects were recruited， by a team of non-governmental organizations （NGO）， at MSM places and voluntary counseling and testing clinics from May to December 2018. The subjects completed a self-administered questionnaire survey on social-demographic， ways to make friends， synthetic drug use， high-risk sexual behavior， and HIV/STD testing history. They also received tests of HIV and syphilis. According to the use of synthetic drugs， they were divided into user group and non-user group.

ResultsA total of 209 subjects were recruited. Among them， 43.1% （90/209） used at least one synthetic drug. 81.3% （170/209） of MSM used internet dating software. The proportion of synthetic drug use was higher among the subjects in 30-34 age group， residence registered in other provinces， with university degree or above， occupation of cadres and staff members， monthly income of more than 10 000 yuan， making friends through gay bars， and acquaintance with male partners. The registered residence in other provinces （OR=3.006） and making friends through gay bars （OR=3.588） were independent factors. The top three synthetic drugs were Rush （90.0%， 81/90）， Viagra （8.9%， 8/90） and “capsule 0” （7.8%， 7/90）. The proportion of having sex after using synthetic drugs was 89.5% （17/19）. The frequency of high-risk sexual behaviors such as oral sex， anal sex without condom and group sex was once a day per person on average.

ConclusionThe use of synthetic drugs is prevalent among MSM， and the frequency of high-risk sexual behaviors after use is high. Warning education on the dangers of synthetic drug use and mobilization for HIV testing should be carried out with the help of new media technology. Special attention should be paid to MSM people in high-income occupations and gay bars.