A case of driving under the influence of drugs with an extremely high blood fentanyl concentration and concomitant use of methamphetamine is presented. As the increase of the appearance of fentanyl in drug seizures continues, the likelihood of tolerant users increases as well. Data presented on fentanyl in antemortem cases over time from several regions of North America show geographic differences on whether fentanyl concentrations are increasing. This case is an example of a blood concentration that could have been assumed to be fatal if presented on its own, a reminder that concentrations, especially those of opioids, must be interpreted with care.
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