Drug abuse refers to the availing of a drug for purposes which the drugs are not intended to, or using a drug in excessive quantities. Drug addiction is a state of physical and psychological dependence on a drug. The physical addiction is often characterized by the presence of tolerance, such as needing more and more of the drug to achieve the same effect, and withdrawal symptoms that disappear when further medication is taken.

Almost all sorts of different drugs can be abused, including illegal drugs, such as heroin or cannabis, preion medicines such as tranquilizers or painkillers and other medications that can be availed off the supermarket shelf, such as cough syrups or herbal concoctions.

This depends on the nature of the drug being abused, the person taking the drug and the circumstances under which it is taken. Some medications, like for example certain sleeping pills or painkillers are physically addictive. They have a specific effect on the body which leads to tolerance and withdrawal symptoms. Others may lead to a psychological addiction if people have a craving for the effect that the drug causes.

There has been some speculation that some people may be more prone to drug abuse and addiction than others. Research is being carried out into whether there may even be genes that predispose certain people to addiction.

More information: http://www.tcmadvisory.com/2008/1-4/200814152529.html