Background: Medical students often face substantial psychological stress, which can increase the risk of substance use, professional detriment, and insufficient patient care. However, substance use in medical students remains understudied in Iraq. This study highlights the prevalence, patterns, risk factors, and negative effects of substance use among medical students at the University of Baghdad. A cross-sectional study involving 414 medical students at the University of Baghdad was conducted. The questionnaire included sociodemographic variables and the Alcohol, Smoking, and Substance Involvement Screening Test to screen for psychoactive substance use. The lifetime prevalence of substance use was 38.9%. Among substance users, 42.8% used nicotine, 22.3% used sedatives, 4.3% used inhalants, and 3.1% used amphetamines, with only 27.3% reporting polysubstance use. Through multivariate logistic regression, it was identified that males are approximately 2.8 times more likely to use substances compared to females (OR: 2.8, 95% CI: 2.1–5.2, p-value < 0.001), and students with a positive family history of substance use are approximately 3.1 times more likely to use substances compared to those without (OR: 3.1, 95% CI: 2.8–7.5, p-value < 0.001). These findings underscore the importance of implementing early preventive strategies, targeted mental health interventions, and substance use awareness programs within Iraqi medical institutions.
