The terms opioid-tolerant and opioid-naïve are used to distinguish between patients who have, or have not, respectively, been taking opioid drugs regularly. An opioid-tolerant person has taken opioids long enough at doses high enough to develop tolerance to many of the effects of an opioid, including analgesia and sedation (Pasero, Quinn, Portenoy, McCaffery, & Rizos, 2011). There is great variation among individuals, however, with some not developing tolerance at all (Webster & Dove, 2007). Therefore, it is difficult to determine if and when an individual on regular doses of opioids has become tolerant. Consequently, there is no widely accepted definition for classifying a patient as opioid-tolerant (Patanwala, Jarzyna, Miller, & Erstad, 2008). By convention, many clinicians consider a patient who has used opioids regularly for approximately 7 days or more to be opioid-tolerant (Pasero, Quinn, Portenoy, McCaffery, & Rizos, 2011).