There are number of ways through which drugs can be administered such as sniffing, through injection trough skin and even through eyes. In brain enormous neurons are connected through synapses. In synapses chemo transmitters are transmitted from one neuron to other so they conduct impulse this way and aware human brain about position, fear and brain made the action in accordance with the situation.Use of illicit Drugs

When we use illicit drug through any of the above mentioned way, it reach to the brain and attached to the receptors of chemo transmitters. This way, with the passage of time the drug dependency continue to build and finally it become addiction.

Normally, when majority talks about substance abuse, they point out the illegal drugs. According to the professionals, those illegal drugs can be placed at the top position because they are potentially addictive and cause severe adverse health effects. Therefore, any use of illegal substances is dangerous and abusive.

With drug addiction, people desire the enjoyable sensation produced by a drug and use it, by all means, despite of its negative consequences.

The drug physical addiction or dependence means that, the drug is uttermost required for the normal functioning of the body. In such case, when the drug is withdrawn, the addict may experience mild to severe effects ranging from nausea to death.

Substance abuse

Only illegal drugs cannot be categorized as abused substances alcohol abuse, prescription and OTC drugs, inhalants and solvents, and even normal coffee and cigarettes, can also cause harmful effect, if used in excessive quantity. Theoretically, almost any substance can be abused.

In case of many substances the demarcation line between use and abuse in unclear. Generally in these kinds of situations, only the individual himself can draw the line from where use ends and abuse begins.

When we talk about illegal substances, researchers as well as society has clearly determined that their use is harmful to health, and has placed legal preventions on their use so as to protect the individual and human society from the costs involved with healthcare resources, lost output, the spread of diseases, crime and homelessness.