Approximate conversion factors
| Opioid | Multiply by |
|---|
| Codeine, dihydrocodeine, tramadol (oral) | 0.1 |
| Tapentadol (oral) | 0.4 |
| Morphine (oral) | 1 |
| Oxycodone (oral) | 1.5 |
| Hydromorphone (oral) | 5 |
| Buprenorphine or fentanyl patch (micrograms/hour) | 2.4 |
Why OME matters
Opioids Aware notes that harms rise steeply above 120 mg a day OME, with little extra benefit. Use the total to guide review and tapering.
Conversions are approximate. When switching opioids, reduce the calculated dose to allow for incomplete cross-tolerance.
Frequently asked questions
What is an oral morphine equivalent?
The daily dose of oral morphine that gives a similar effect to a person’s total opioids.
What OME is high risk?
Above 120 mg a day, harms increase without much extra benefit (Opioids Aware).
Can I use this to switch opioids?
Only as a guide. Reduce the new dose and seek specialist advice when needed.
References
- Faculty of Pain Medicine. Opioids Aware. fpm.ac.uk
- BNF. Prescribing in palliative care.
MedToolbox supports, and does not replace, clinical judgement, national guidance and local policy.
