Inappropriate self-medication among adolescents and its association with lower medication literacy and substance use.

While self-medication is common, inappropriate self-medication has potential risks. This study assesses inappropriate self-medication among adolescents and examines the relationships among medication literacy, substance use, and inappropriate self-medication.In 2016, a national representative sample of 6,226 students from 99 primary, middle, and high schools completed an online self-administered questionnaire. Multiple logistic regression analysis was used to examine factors related to inappropriate self-medication.The prevalence of self-medication in the past year among the adolescents surveyed was 45.8%, and the most frequently reported drugs for self-medication included nonsteroidal anti-inflammatory drugs or pain relievers (prevalence = 31.1%), cold or cough medicines (prevalence = 21.6%), analgesics (prevalence = 19.3%), and antacids (prevalence = 17.3%). Of the participants who practiced self-medication, the prevalence of inappropriate self-medication behaviors included not reading drug labels or instructions (10.1%), using excessive dosages (21.6%), and using prescription and nonprescription medicine simultaneously without advice from a health provider (polypharmacy) (30.3%). The results of multiple logistic regression analysis showed that after controlling for school level, gender, and chronic diseases, the participants with lower medication knowledge, lower self-efficacy, lower medication literacy, and who consumed tobacco or alcohol were more likely to engage in inappropriate self-medication.Lower medication literacy and substance use were associated with inappropriate self-medication among adolescents.