Introduction Substance use to enhance sexual pleasure and performance is well known among men who have sex with men (MSM). Studies report a higher Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) prevalence among MSM who use substance before or during sex. Limited data exist on substance use in relation to CT and NG prevalence among young heterosexuals.

Methods CT and NG tested men and women aged <25 years attending our STI-clinic between 2010- 2015 were included (n=3526). Specimens were tested using nucleic acid amplification tests. Data were collected on demographics, sexual behaviour, smoking, alcohol intake and drug use; marihuana, gamma hydroxy butyrate (GHB), ketamine, cocaine, heroin, speed, ecstasy and poppers. Univariable and multivariable backward logistic regression analyses were used to test associations between substance use and CT/NG. Tested determinants were age, symptoms, number of sex partners and warned by (ex) partner.

Results CT prevalence was 13.6% (n=300) for women, 15.4% (n=153) for heterosexual men and 10.6% (n=35) for MSM. For NG this was 1.0% (n=23), 1.4% (n=14), and 15.8% (n=52) respectively. Substance use before or during sex varied between 26%–40% for drugs, 44%–67% for alcohol and 51%–64% for cigarette smoking. Among drug users, 39%–45% used multiple drugs, most often marihuana (84%), ecstasy (81%) and cocaine (51%). In young heterosexuals, smoking was independently associated with CT in women (OR 1.3 95% CI 1.1–1.7), and ketamine use in men (OR 4.5, 95% CI 1.6–12.7). For MSM, GHB use was independently associated with CT (OR 3.8, 95% CI 1.2–12.2) and ketamine use with NG (OR 4.7, 95% CI 1.3–16.9).

Conclusion Substance use before or during sex was reported often among young heterosexuals and MSM, and led to greater CT and NG (for MSM) risk. Different substance use was associated with different STI in different risk groups, therefore targeted care is an imperative. Prevention in STI clinics should include discussing drug use before or during sex, also in heterosexual youngsters.