Coloured preparations reflect different contaminants present. While the drug can be used orally it is more often used parenterally because this is a far more cost effective means of achieving the desired psychoactive effects. The onset of action is rapid and the duration of action is approximately 3-4 hours. The immediate effect or 'rush' after an IV dose is related to the high fat solubility of the drug and thus its rapid entry into the brain. As heroin is not legally available in Australia, illegal users obtain supplies of the drug on the street.
Most users inject their dose using a number of solvents for the powder they purchase.
It is apparent that treating an individual who shoots up four times a day with heroin would prove very difficult if each dose had to be supervised. Many illicit users are unable to obtain regular doses every day and will substitute heroin with other CNS depressants, typically benzodiazepines. Apart from the risk of overdose which is a direct CNS effect of the drug, most complications of heroin use relate to the injection of contaminated material, or the use of non-sterile injecting equipment. A number of alternatives are available to those who are opioid-dependent. The natural history of opiate dependence indicates that many do grow through their period of dependence irrespective of treatments offered.