Heroin
is an illegal, highly addictive drug. It is both the most abused and
the most rapidly acting of the opiates. Heroin is processed from morphine,
a naturally occurring substance extracted from the seed pod of certain
varieties of poppy plants. It is typically sold as a white or brownish
powder or as the black sticky substance known on the streets as "black
tar heroin." Although purer heroin is becoming more common, most street
heroin is "cut" with other drugs or with substances such as sugar,
starch, powdered milk, or quinine. Street heroin can also be cut with
strychnine or other poisons. Because heroin abusers do not know the
actual strength of the drug or its true contents, they are at risk
of overdose or death. Heroin also poses special problems because of
the transmission of HIV and other diseases that can occur from sharing
needles or other injection equipment.
Heroin
is usually injected, sniffed/snorted, or smoked. Typically, a heroin
abuser may inject up to four times a day. Intravenous injection provides
the greatest intensity and most rapid onset of euphoria (7 to 8 seconds),
while intramuscular injection produces a relatively slow onset of euphoria
(5 to 8 minutes). When heroin is sniffed or smoked, peak effects are
usually felt within 10 to 15 minutes. Although smoking and sniffing
heroin do not produce a "rush" as quickly or as intensely as intravenous
injection, NIDA researchers have confirmed that all three forms of heroin
administration are addictive. Route of Administration Among Heroin Treatment
Admissions in Selected Areas Source: Community Epidemiology Work Group,
NIDA, December 1999 Injection continues to be the predominant method
of heroin use among addicted users seeking treatment; however, researchers
have observed a shift in heroin use patterns, from injection to sniffing
and smoking. In fact, sniffing/snorting heroin is now the most widely
reported means of taking heroin among users admitted for drug treatment
in Newark, Chicago, and New York. With the shift in heroin abuse patterns
comes an even more diverse group of users. Older users (over 30) continue
to be one of the largest user groups in most national data. However,
the increase continues in new, young users across the country who are
being lured by inexpensive, high-purity heroin that can be sniffed or
smoked instead of injected. Heroin has also been appearing in more affluent
communities.

References:
National Institutes On Drug Abuse (NIDA), U.S. Department of Health
and Human Services · National Institutes of Health