To become dependent upon chemicals such as illicit drugs and/or alcohol is to put your health at risk. Chemical dependency is a condition in which the use of mood altering substances such as drugs or alcohol is associated with problems in any area of life on a more or less continuing basis.
One does not, however, have to be addicted or chemically dependent to suffer health risks from the use of illicit drugs or alcohol.
Alcohol and illicit drugs (in all the many forms) may, and often do, impair physical coordination and judgment, diminish control over impulsive behavior, and cause many short- and long-term health consequences.
Alcohol‑related illnesses now represent the third leading cause of death in the United States exceeded only by cancer and heart disease, and medical research has established very strong evidence that alcohol abuse contributes significantly to cancer and heart disease. There is clear evidence of serious negative effects on babies due to use of illicit drugs and alcohol by the mother during pregnancy.