Addiction (also referred to as dependence syndrome, drug dependence, psychological dependence, or substance dependence) refers to a maladaptive pattern of behaviors and compulsive use of drugs despite harm. Addiction is distinct from analgesic tolerance or physical dependence, although the phenomena may co-occur (e.g., in heroin addicts). Neither analgesic tolerance nor physical dependence is sufficient to characterize addiction. Addiction is a biopsychosocial condition and evidence shows that it is not more common in patients with chronic pain from cancer than in the general population. Addiction is not a side effect, or an expected consequence, of opioid use.