Preanesthetic Opioids and Subjective Effects Before Induction
Giving a small opioid dose before induction remains common in many operating rooms, partly out of habit and partly in the hope that patients will feel calmer on the way into the OR. A September 2026 open-access randomized trial in Cell Reports Medicine examined that habit more closely by asking what elective surgical patients actually report feeling in the minutes after intravenous morphine, oxycodone, or fentanyl.
About 199 ASA I or II adults received a standardized multimodal preoperative medication and were then randomized to morphine 10 mg, oxycodone 5 mg, or fentanyl 0.1 mg IV. They rated effects on 0 to 10 scales immediately before and three minutes after the opioid. Comfort was not the dominant finding. Intoxication, sedation, and dizziness led the list, and nearly everyone (about 96%) reported feeling intoxicated. Only about 23% said they felt better overall, and desirable effects such as reduced anxiety or greater relaxation were modest. Fentanyl tended to score highest for intoxication, sedation, dizziness, and euphoria; morphine scored lower, and oxycodone usually fell in between. Interindividual scatter was large in every arm.
How I read this as a clinician
This trial does not prove that pre-induction opioids never help an individual patient. It does challenge the casual assumption that a “little fentanyl now” reliably improves the preoperative experience. If most patients feel intoxicated and few feel better, the default justification for routine preanesthetic opioids becomes considerably weaker, especially when multimodal anxiolysis, clear communication, and non-opioid adjuncts are already available.
The limits of the study deserve equal attention. It did not examine intraoperative analgesia, emergence, or postoperative opioid requirements; it addresses the minutes before induction. That is still a clinically meaningful window, because it shapes how we talk with patients, how we document informed comfort measures, and how we avoid layering early opioid effects onto induction hemodynamics without a clear benefit.
Implications for practice
In this RCT, pre-induction morphine, oxycodone, and fentanyl produced mainly undesirable subjective effects, chiefly intoxication, sedation, and dizziness, with only modest desirable effects. Almost all patients reported intoxication, and only about one in four reported feeling better. In this dosing comparison, the subjective intensity of fentanyl was generally higher than that of morphine, with oxycodone intermediate.
The large person-to-person variability argues against a uniform habit of always giving a premedication opioid. I would reserve pre-induction opioids for a clear indication and rely on non-opioid strategies when the goal is anxiolysis or comfort rather than analgesia for painful stimuli.
Source
- Intoxication and other subjective effects of preanesthetic opioids in surgical patients: A randomized controlled trial. Cell Reports Medicine. Published online September 11, 2026 (EudraCT: 2020-004920-40). Full text
This post is clinician commentary for educational discussion. It is not medical advice for any reader’s personal care. Anesthesia and perioperative decisions should be made with the treating clinician based on the individual patient’s circumstances.