# Strong opioids for cancer pain: starting, titrating, rescue doses and preventing constipation

Source: https://onco.cc/protocols/strong-opioids-for-cancer-pain/  
OnCo record `strong-opioids-for-cancer-pain` (Protocol). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

When cancer pain needs a strong painkiller, morphine by mouth is usually the first choice: a regular dose plus extra 'rescue' doses for pain that breaks through, adjusted until the pain is controlled with side effects you can live with. A laxative should be prescribed from the start, because almost everyone taking strong opioids gets constipated.

## Summary

NICE CG140 (2012, updated 2016) and WHO (2018) agree on the core: oral morphine first, regular dosing with immediate-release oral morphine for rescue (WHO strong recommendation, moderate-quality evidence). NICE gives a starting schedule for adults without renal or hepatic impairment of 20 to 30 mg oral morphine a day with 5 mg immediate-release rescue doses during titration, and asks for specialist advice before strong opioids in moderate to severe renal or hepatic impairment. ASCO 2023 starts PRN at the lowest dose with early assessment and frequent titration; the Australian guideline (2025) adds ASCO's minimum dose increase of 25 to 50% and NCCN's practice of folding the previous 24 hours of rescue doses into the regular dose.

Rescue doses are where the sources differ most in their numbers: WHO suggests 50 to 100% of the regular 4-hourly dose; the Australian guideline, citing ASCO 2022, 5 to 20% of the daily regular dose, up to hourly; NICE gives a fixed 5 mg during titration and says not to use fast-acting fentanyl as first-line rescue. Every patient starting a strong opioid should be prescribed a regular laxative (NICE 1.1.18); NICE says to optimise laxatives before switching opioids, and points to naldemedine and naloxegol appraisals for constipation that persists despite laxatives. Nausea and drowsiness at the start or after a dose rise are usually transient; persistent central nervous system effects call for dose reduction if pain is controlled or a switch if it is not.

The ESMO 2018 guideline, which the Australian guideline draws on heavily, could not be read directly.

## Fields

- Kind: Protocol
- Last checked: 2026-11-11
- Also known as: starting morphine for cancer pain; opioid titration; breakthrough cancer pain; rescue dose; PRN morphine; opioid-induced constipation prevention; laxative with opioids; WHO analgesic ladder

## Connected records

- protocols: [Care in the last days of life: recognising dying, hydration, symptom control and anticipatory medicines](https://onco.cc/protocols/care-in-the-last-days-of-life/), [Opioid switching and dose conversion in adults with cancer pain](https://onco.cc/protocols/opioid-switching-and-conversion/), [Syringe driver (syringe pump): setting up and checking a continuous subcutaneous infusion in palliative care](https://onco.cc/protocols/syringe-driver-continuous-subcutaneous-infusion/)
- technologies: [Cancer pain management](https://onco.cc/technologies/pain-management/), [Early integrated palliative care](https://onco.cc/technologies/palliative-care/)
- drugs: [Fentanyl (transmucosal, for breakthrough cancer pain)](https://onco.cc/drugs/fentanyl/), [Methylnaltrexone](https://onco.cc/drugs/methylnaltrexone/)

---
JSON: https://onco.cc/api/v1/entities/strong-opioids-for-cancer-pain.json