In 1999, the average age of an adolescent in treatment at Caron for heroin addiction was about 17, with some patients as young as 14. During that same period, adult heroin users in treatment at Caron had an average age of 29 - a full 10 years younger than the average age of 39 for those admitted for other drug or alcohol treatment.

Heroin overdose takes the lives of many users each year. It is not a surprise that those who abuse heroin are at an increased risk of death. Their excess mortality rate ranges between six to twenty times their peers who are of the same age and gender and have not abused heroin. The causes of this excess mortality are manifold, including HIV/AIDS, hepatitis and violence. Despite the HIV pandemic among injecting drug users, deaths attributed to overdose remain a major cause of mortality for heroin users, and in many countries is the leading cause of death. Typically, males are the most predominant casualties of a heroin overdose. With around 80% of heroin overdose deaths reported being male.

The various physical effects of methamphetamine include, increased energy, change in libido, increased sweating, decrease in appetite (anorexia), insomnia, dilated pupils, tightened jaw muscles (trismus), teeth grinding (bruxism), itching, nausea, vomiting, diarrhea, shortness of breath, involuntary body movements (twitches, grimacing, lip smacking, etc), increased heart rate, increased blood pressure, vasoconstriction, dry mouth, and a difficulty in urination. Serious physical effects include, possibly fatal lung and kidney disorders, possible brain damage, lowered resistance to illnesses, liver damage, heart attack, and stroke.

Approximately 100 years after cocaine entered into use, a new variation of the substance emerged. This substance, crack, became enormously popular in the mid-1980s due in part to its almost immediate high and the fact that it is inexpensive to produce and buy.