Abstract
Tolerance to the analgesic effects of opioids after the first days of therapy is unusual. Several factors may result in an increased dose requirement that is not true tolerance. This phenomenon may be described as psuedotolerance. These factors include progression or exacerbation of the underlying disease, new pathology related or unrelated to the original disease, increased physical activity, lack of compliance with the physician's directions, change in the medication formulation (brand or supplier), drug interaction, addiction, and diversion