Today, present international illegal heroin trade can be traced back to laws passed in many countries in the early 1900s that closely regulated the production and sale of opium and its derivatives including heroin.
Trafficking heroin carries a conviction of the death penalty in most South-east Asian, some East Asian and Middle Eastern countries, among which Malaysia, Singapore and Thailand are the strictest.
Users who snort heroin experience the onset of its effects within 3 to 5 minutes. Those who smoke the drug experience an almost immediate effect that builds in intensity; intravenous injection of heroin induces a rush and euphoria usually taking effect within 30 seconds; intramuscular and subcutaneous injection of heroin takes effect within 3 to 5 minutes.
Using heroin is often a ritualized behavior. While the mechanism has yet to be clearly elucidated, longtime heroin users display increased tolerance to the drug in locations where they have repeatedly administered heroin. When the user injects in a different location, this environment-conditioned tolerance does not occur, resulting in a greater drug effect. The user's typical dose of the drug, in the face of decreased tolerance, becomes far too high and can be toxic, leading to overdose.
Withdrawal symptoms will appear if continued use of heroin is stopped abruptly, even after just three days of using the drug.