Traditionally used for treating illness and alleviating physical and mental stress, opium was outlawed in many countries in the region in the years following World War II, forcing many habitual users to switch to heroin. Over the past twenty years, there has been an increasing trend towards drug abuse among youth, often involving multiple drug use such as the abuse of heroin and other opiates as a problem of epidemic proportion. While most abusers had inhaled and smoked these drugs, there has recently been an increased incidence of injecting high purity heroin. Urban populations were the initial centers of heroin addiction, but the problem soon spread to other cities, towns, and even to hill tribes, as studies in Thailand have demonstrated. Recent studies reveal that heroin abuse has also spread to countries which had no previous experience with the problem, including India and Sri Lanka. Addicts have begun to use manufactured psychotropic substances when heroin is difficult to obtain. Opium use in China and the problem of methamphetamine abuse in Japan is also discussed. 1 table, 34 references. (Author abstract modified)