Nicotine in cigarettes is by far the most abused substance in the United States. An estimated thirty one percent of the population smoke cigarettes. The second and third most commonly abused substances are alcohol and illegal drugs. People who abuse common chemical substances such as alcohol, cigarettes or drugs often do so on a daily basis. Some substances, such as alcohol and illegal drugs, such as cocaine, are often abused in binges, which means that the substance is used constantly for a period of time and then not used at all for long periods of time.
Substance abuse can vary greatly in terms of how much it affects a person's life.
Each drug affects a person in a different way. A person dependent upon caffeine may need coffee each morning in order to feel awake and ready for the day. While this is an un-healthful habit, it is not likely to cause a person to have difficulty fulfilling his or her other obligations in life, such as work and relationships with family and friends. However, a person who is abusing illegal drugs may not be able to do so without disrupting other parts of his or her life. He or she might have to stop working because of the effects of the drug.