Drug rehabilitation (often shortened to drug rehab or just rehab) is an umbrella term for the processes of medical and/or psychotherapeutic treatment, for dependency on psychoactive substances such as alcohol, prescription drugs , and so-called street drugs such as cocaine, heroin or amphetamines. The obvious intent is to enable the patient to cease their previous level of abuse, for the sake of avoiding its psychological, legal, social, and physical consequences, especially in extreme abuse.
Drug rehabilitation tends to address the two fold nature of drug dependency; physical and psychological dependency. Physical dependency involves a detoxification process to cope with withdrawal symptoms from regular use of a drug. With regular use of many drugs, legal or otherwise, the brain gradually adapts to the presence of the drug so that normal functioning can occur. This is how physical tolerance develops to drugs such as heroin, amphetamines, cocaine, nicotine or alcohol. It is also why more of the drug is needed to get the same effect with regular use. The abrupt cessation of taking a drug can lead to withdrawal symptoms where the body may take weeks, to possibly months (depending on the drug involved) before things get back to normal.
Psychological dependency is addressed in many drug rehabilitation programs by attempting to teach the patient new methods of interacting in a drug free method. In particular, patients are generally encouraged or required not to associate with friends who still use the addictive substance. Twelve-step programs encourage addicts not only to stop using alcohol or other drugs, but to examine and change habits related to their addictions. Many programs emphasize that recovery is a permanent process without a culmination. For legal drugs such as alcohol complete abstention rather than attempts at moderation, which may lead to relapse are also emphasized ("One drink is too many; one hundred drinks is not enough.") Whether moderation is achievable by persons with a history of abuse remains a controversial point but is generally considered unsustainable.
There are various types of programs that offer help in drug rehabilitation, including: residential treatment (in-patient), out-patient, local support groups, extended care centers, and sober houses.
Drug rehabilitation is sometimes part of the criminal justice system. People convicted of minor drug offenses may be sentenced to rehabilitation instead of prison, and those convicted of driving while intoxicated are sometimes required to attend Alcoholics Anonymous meetings.