Drug addiction (dependence) is compulsively using a substance, despite its negative and sometimes dangerous effects. Drug abuse is using a drug excessively, or for purposes for which it was not medically intended.

A physical dependence on a substance (needing the drug to function) is not always part of the definition of addiction. Some drugs (for example, some blood pressure medications) don't cause addiction but do cause physical dependence. Other drugs cause addiction without physical dependence (cocaine withdrawal, for example, doesn't have symptoms like vomiting and chills; it mainly involves depression).

See also:

• Drug abuse
• Drug abuse first aid

Drug addiction; Addiction - drug