Can we use more than one opioid at a time?

I have noticed that a clinical consideration has been removed from the ACP Analgesia medical directive in regards to Morphine and Fentanyl administration. I recall that in previous versions of the ALS PCS it stipulated that you can only administer Morphine or Fentanyl when providing opioid analgesia to a patient, without a patch. I notice this has been taken out, am I now authorized to be able to administer Fentanyl then morphine or vice versa to a patient. An example would be: giving morphine to a patient who then presents with a histamine reaction and I want to switch to Fentanyl, or I have maxed my patient out on Fentanyl and want to continue pain management treatment with Morphine? Thank you

The recent wording change in the ACP Analgesia directive should not be interpreted as permission to stack or sequence maximum doses across fentanyl, morphine, and ketamine. The directive is intended to support a measured, titrated approach to pain control, not escalation to each opioids maximum.

In practice, select a primary opioid and titrate to effect within its dosing limits. If analgesia remains inadequate after the maximum single dose of opiooid, Ketamine is an appropriate adjunct and should be considered. An opioid plus ketamine, used together in a balanced approach, is well supported and often provides better analgesia while limiting further opioid exposure.

Where clarification is important is opioid rotation. Reaching the maximum dose of fentanyl would not typically prompt switching to morphine, or vice versa, simply to continue escalating opioid dosing. If additional opioid beyond standard maximums is being considered, Base Hospital Physician consultation is the appropriate pathway rather than moving laterally between opioids.

This is also an opportunity to reinforce fentanyl as the preferred first line opioid in most prehospital contexts. Its rapid onset, short duration, and minimal histamine release make it more hemodynamically stable than morphine, particularly in trauma, shock, or borderline perfusion states. More predictable titration and reduced vasodilatory effect support its use as the primary agent in most adult analgesia presentations.

There are uncommon situations where switching opioids may be reasonable for safety, for example a suspected histamine mediated reaction with morphine. In those cases, substitution should be based on clear clinical rationale and documented accordingly.