Opioid toxicity should be managed initially by decreasing the opioid dose

EDITOR—We would like to clarify some important points arising from Murray's letter about the substitution of another opioid for morphine being of use in pain control.1 The first is the description of pain being “relatively resistant to morphine.” It is more useful to think of responsiveness to opioids as a continuum; the factors that generally decide the position on the continuum are the side effects of opioids, particularly sedation.2 Some pains, especially neuropathic pain, require larger doses of opioids, which consequently give rise to more troublesome side effects and thus limit an escalation of the dose and the achievement of adequate analgesia. Opioid toxicity results from an unfavourable balance between analgesia and the side effects of opioids.

While alternative opioids may produce a better outcome,3 the safest and most efficient management of opioid toxicity is to reduce …