To examine the trends of substance use and correlated variables in high-school students in Southern Thailand.
Surveys of high-school years 7, 9 and 11 and vocational school year 2 students in four provinces in Southern Thailand were conducted in 2002–2004 to examine lifetime substance use, use within 1 year and 30 days before the interview, using a self-completed questionnaire.
The prevalence of lifetime use of any illicit substance was 5–7 % overall (about 7 % , 9 % and 13 % in boys and 2 % , 1 % and 3 % in girls in 2002, 2003 and 2004, respectively). Krathom, a local addictive plant, and cannabis were the most commonly used illicit substances on a lifetime basis with prevalences of 2.3 % , 2.8 % , 4.9 % (p < 0.01) and 2.6 % , 2.3 % , 3.4 % (p > 0.05) in the surveyed years. The rates of alcohol consumption in the past 30 days were 19.3 % , 17.3 % and 15.2 % (p > 0.05) while smoking rates were 14.6 % , 8.8 % and 10.8 % (p < 0.05). The significant correlates of current illicit substance use were surveyed year, male, vocational school, school level, and school performance.
The problem of substance abuse is increasing among Thai adolescents. School-based interventions seem desirable, especially in boys, vocational and public school students.