The continuum of substance use ranges from abstinence to dependence. People start and continue to use drugs for many reasons. Those reasons can change over time. People do not necessarily move along the continuum, but rather can stay at one point for extended periods of time or cycle through different points along the continuum. People who are polysubstance users (i.e., use multiple types of drugs) can be at different points along the continuum for different substances.

Information adapted from the Ontario HIV & Substance Use Training Program
No Use (abstinence)
The person does not use any substances.
Experimental Use
The person tries a substance and may or may not use it again.
Social or Occasional Use
The person uses the substance infrequently.
Medication (prescribed)
The person is prescribed and uses a medication as directed by a medical practitioner; medical supervision is provided minimizing risk of adverse outcomes.
Problematic Use
The person experiences negative consequences from using a substance (e.g., health, family, school, work, financial, legal problems).
Dependence
The person is dependent on a substance and continues using, despite experiencing serious problems. Withdrawal symptoms may exhibit if use stops.