Electrotransport drug delivery devices, systems and methods for delivery of lofentanil or carfentanil are disclosed. The lofentanil or carfentanil may be provided as a water soluble salt (e.g., lofentanil or carfentanil hydrochloride), such as in a hydrogel formulation. A transdermal, electrotransport delivered dose of lofentanil or carfentanil is provided which is sufficient to induce analgesia in (e.g., adult) human patients suffering from chronic, acute and/or breakthrough pain.