The WHO defines drug dependence as:
A state, psychic and sometimes physical, resulting from taking a drug, characterised by behavioural and other responses that always include a compulsion to take a drug on a continuous or periodic basis in order to experience its psychic effects, and sometimes to avoid the discomfort of its absence. Tolerance may or may not be present, and a person may be dependent on more than one drug.
Otherwise, drug dependence may be described as compulsive drug use which takes priority over considerations of personal health or social obligations.
Last reviewed 01/2018