Drug abuse or substance abuse is a disorder characterised by excessive use of habit forming drugs or misuse of over the counter medicine, illegal use of drugs which in turn leads to severe addiction and dependence with many negative consequences, drug addiction is a chronic illness with relapse rates similar to those of hypertension, diabetes, and asthma. We now know that while the initial decision to use drugs is voluntary, drug addiction is a disease of the brain that compels a person to become singularly obsessed with obtaining and abusing drugs despite their many adverse health and life consequences. Treatment of substance abusers depends upon the severity and nature of the addiction, motivation, and the availability of services. Substance abuse may increase vulnerability to mental illness; Relapses to drug abuse can occur during or after successful treatment episodes, Participation in self-help support programs during and following treatment can be helpful in sustaining long-term recovery. Some people uses recreational or prescription drugs without ever experiencing addiction and its negative consequences, some drugs of abuse have a mechanism of action similar to that of drugs used as psychotherapeutic agents. Most experts feel that addiction is a brain disease. The brain changes associated with addiction can be treated and reversed through therapy, medication