Heroin addiction is what happens when an individual becomes dependent upon the opioid, heroin, to carry out his or her day to day activities. By definition, addiction implies a problem; people who are addicted or dependent upon a drug like heroin but are still functional in their day to day lives are rare. Heroin is a semi-synthetic opioid that is derived from the same chemical as oxycodone, hydrocodone, and morphine.
Heroin can be taken into the body via intravenous injection or via the mucous membranes of the body (most commonly the nose). Almost immediately after the chemical enters the body, it crosses the blood-brain barrier. The brain, sensing the opioid, transforms the heroin into morphine. The morphine then binds to the body's opiate receptors, creating a high. This high, or "rush," happens very quickly and is very euphoric for individuals that experience it.
The individual continues to search for this euphoric feeling after the high wears off, but each time he or she takes an opiate, he or she needs to take more to achieve the same feeling. This is called heroin dependency. The continued use of heroin for non-medical purposes is called heroin abuse. The combination of abuse and dependency is what is known as heroin addiction. Finding heroin addiction treatment for individuals with opiate problems is easy, but heroin users are particularly prone to relapse.