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What must be considered in coadministration of morphine and fentanyl?

Question# 742

Under analgesia directive, It sates, "Fentanyl should not be used in combination with morphine unless authorized by BHP." Is this specific to co-administration? For example, we treated a fracture with fentanyl on scene to splint and extricate the patient. Then we sat on offload delay at the hospital for an extended time. We had maxed out the fentanyl total dose due to ongoing spasms of the muscle and clearly not coping with the discomfort. We ended up patching to a BHP to switch to morphine for longer acting analgesia and it was approved, but I just wonder if a patch was even required. It wouldn't be contraindicated to treat someone's renal colic with morphine if they admitted to using fentanyl before we arrived, obviously we would take this into consideration when dosing and reassessing the patients. Just wondering if we are allowed to switch without a patch if we administer the drugs as long as we respect onset times, durations, low and slow dosing, and do not "co-administer" both.


Fentanyl is an excellent analgesic choice for rapid control of pain to facilitate splinting and extrication, as its onset of analgesia is almost immediate, and it has less negative effects on blood pressure than morphine. Morphine, however, lasts for longer, and provides analgesic effects within 5 to 10 minutes. Both fentanyl and morphine have been shown to be safe and effective for out-of-hospital analgesia.

Fentanyl is 100 times as potent as morphine, thus co-administration at the maximum doses in the ALS PCS, would be double the recommended opioid dose, causing significant respiratory, cardiovascular and CNS depression risk to the patient. It is, therefore, not recommended. Rather, it is recommended to use multimodal analgesia where possible; i.e. the co-administration of opioids, NSAIDs and acetaminophen.

There are occasions when it may be beneficial to switch between opioids, e.g. from fentanyl to morphine when on a long offload delay, however this requires a patch to the BHP. The purpose of the patch, at RPPEO, is for the paramedic and physician to consult on the positive and negative effects the opioid has had on the patient, and to proceed cautiously with the addition of another opioid. Since analgesia has already been administered and any urgent actions would be completed, the patch is unlikely to be burdensome on the paramedic nor cause delay to patient care.

It may be considered that patients with opioid use disorder who have recently taken opioids are essentially having co-administration if a paramedic administers opioid analgesia. However, these patients typically require higher doses of opioids to achieve analgesia and, therefore, cannot be compared to patients who are opioid naïve. For patient safety, it is best to consult with a BHP before adding opioid analgesics, as is required by the analgesia medical directive.


Patient Care Standards:

Analgesia Medical Directive (ACP) > Clinical Considerations:

Fentanyl should not be used in combination with morphine unless authorised by BHP


Fleischman, RJ, et al, 2010. Effectiveness and Safety of Fentanyl Compared with Morphine for Out-of-Hospital Analgesia. Prehospital Emergency Care.
Lexicomp, 2023. Fentanyl: Drug information.
Lexicomp, 2023. Morphine: Drug information.
Pandharipande, P. & Hayhurst, CJ, 2023. Pain control in the critically ill adult patient. UpToDate.
RPPEO, 2022. Should opioid analgesia be administered to a patient with opioid use disorder? MedicASK.


07 November 2023

ALSPCS Version




Please reference the MOST RECENT ALS PCS for updates and changes to these directives.