Background and Objectives: Self-medication with over-the-counter (OTC) medicines is becoming an increasingly popular practice around the world. The global prevalence rate of self-medication ranges from 11.2% to 93.7%, depending on the target population and country. However, there is a lack of data on the prevalence and practices of self-medication among the working-age population, particularly in Thailand metropolitan areas. The current study describes the prevalence of self-medication practices, adverse drug reactions and severity, reasons for self-medication, and basic medication knowledge among people of working age in metropolitan areas in Thailand.Methods: We conducted an online cross-sectional study between December 2020 and January 2021. Descriptive statistics were used to analyze self-medication data. A chi-square test was used to assess the association between self-medication and sociodemographic characteristics.Results: This study found high prevalence of self-medication among the working-age population in metropolitan areas of Thailand (88.2%). The most commonly used drug groups were NSAIDs (34.8%) and antibiotics (30.2%). Minor illness and easy access to pharmacies were the most common reasons for self-medication. Almost half of the participants' illnesses (42.6%) for which they self-medicated were not always completely cured, necessitating treatment at a hospital or clinic. Although only a small number of participants (ranged from 0.6 to 6.6%) experienced adverse drug reactions as a result of self-medication, some had severe symptoms that disrupted their daily lives or required hospitalization. In terms of basic medication knowledge, we discovered that study participants misunderstood some antibiotic drug concepts.Conclusions: According to the study findings, it is recommended that more information about the risks of self-medication, drug adverse reactions, antibiotic stewardship, more supervision of the prohibition of over-the-counter drugs and selling practices, and adequate facilities for peoples access to medical services be provided at the policy level.

Purpose The purpose of this paper is to determine the effectiveness of a modified HBM-based intervention to reduce body mass index (BMI) for age in overweight junior high school students. Design/methodology/approach A cluster-randomized controlled trial was conducted in the first and second years of a junior high school in the center of Thailand. In total, 24 classrooms were randomly assigned to a modified health belief model intervention arm (HBMIA), and 24 classrooms were randomly assigned to a traditional school health education arm (control). In total, 479 students who were overweight (BMI forage = median +1 SD, aged 12–15 years) participated in the study. The HBMIA used the health belief model (HBM) as a motivator for behavioral strategies that included modifying diet and participating in physical activity. BMI, health knowledge and behavior for preventing obesity were recorded at baseline and at six months. A multilevel regression model was performed to calculate mean difference between HBMIA and control group. Findings The students who participated in the HBMIA showed a decrease in BMI of 1.76 kg/m2, while those who participated in the control showed an increase in BMI of 1.13 kg/m2, with a mean difference of –2.88 kg/m2 (95% CI =–3.01 to –2.75), an improvement in health knowledge (mean difference 27.28; 95% CI =26.15–28.41) and an improvement in health behavior (mean difference 23.54; 95% CI =22.60–24.48). Originality/value A modified HBM-based intervention to reduce BMI for age is effective in overweight junior high school students.