A MedicationStatement may be used to record substance abuse or the use of other agents such as tobacco or alcohol. This would typically be done if these substances are intended to be included in clinical decision support checking (for example, interaction checking) and as part of an active medication list. If the intent is to populate social history and/or to include additional information (for example, desire to quit, amount per day, negative health effects), then it is better to record as an Observation that could then be used to populate Social History.