{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,9]],"date-time":"2026-10-09T16:04:42Z","timestamp":1791561882461,"version":"4.3.4"},"reference-count":49,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2025,12,30]],"date-time":"2025-12-30T00:00:00Z","timestamp":1767052800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>Background: Adolescents face unique challenges as they transition from childhood to adulthood, which can be marked by risky behaviours such as substance use and sexual activities. The present study analyses the relationship between risky sexual behaviour and the use of psychoactive substances, namely alcohol, cannabis, and other illegal substances, among students aged 15\u201316 years in 23 European countries, to investigate potential between-country differences. Method: Data were extracted from the 2019 European School Survey Project on Alcohol and Other Drugs (ESPAD) cross-sectional survey. Risky sexual behaviour was defined as self-reported unprotected sex. Substance use, other individual risk behaviours, and parenting indicators were investigated as key predictors. Results: A 9.8% of 16-year-old students in Europe reported sexual intercourse without a condom in the past year, and 7.8% had unprotected sex while not using alcohol\/drugs, with a higher prevalence observed among males (8.5%) than among females (7.1%). Prevalence ranged from 3.2% in Georgia to 16.0% in Sweden. The multivariate analysis revealed significantly higher odds of engaging in sexual intercourse without a condom in illicit drug users (cannabis, inhalants, cocaine, ecstasy) and heavy episodic drinkers, students who went out in the evening, and those belonging to non-traditional families. Conclusions: Unprotected sex in the past year and substance use are strongly associated amid 16-year-old students in Europe. The prevalence of risky sexual behaviours across European countries does not follow a clear geographical pattern, suggesting that simple macro-level factors, such as broad regional or cultural groupings, may only partially explain prevalence differences.<\/jats:p>","DOI":"10.3390\/ijerph23010048","type":"journal-article","created":{"date-parts":[[2025,12,31]],"date-time":"2025-12-31T16:08:00Z","timestamp":1767197280000},"page":"48","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Unprotected Sex and Its Association with Other Risky Behaviours Among European Students: A Multinational Study"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7470-2422","authenticated-orcid":false,"given":"Marco","family":"Scalese","sequence":"first","affiliation":[{"name":"Institute of Clinical Physiology, National Research Council, 56124 Pisa, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-6647-414X","authenticated-orcid":false,"given":"Benedetta","family":"Ferrante","sequence":"additional","affiliation":[{"name":"Institute of Clinical Physiology, National Research Council, 56124 Pisa, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0774-8586","authenticated-orcid":false,"given":"Sonia","family":"Cerrai","sequence":"additional","affiliation":[{"name":"Institute of Clinical Physiology, National Research Council, 56124 Pisa, Italy"},{"name":"Department of Epidemiology, Care and Public Health Research Institute (CAPHRI), Maastricht University, 6229 Maastricht, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7221-0873","authenticated-orcid":false,"given":"Sabrina","family":"Molinaro","sequence":"additional","affiliation":[{"name":"Institute of Clinical Physiology, National Research Council, 56124 Pisa, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1664","DOI":"10.1177\/09567976221102070","article-title":"Real-World Exploration Increases Across Adolescence and Relates to Affect, Risk Taking, and Social Connectivity","volume":"33","author":"Cohen","year":"2022","journal-title":"Psychol. 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