Opioid/opiate conversion tables – switching between opioid medicines

Scottish Palliative Care Guidelines
Healthcare Improvement Scotland

Seek specialist advice if uncertain

  • These doses/ratios are approximate (≈) and not exact equivalent doses and should be used as a guide.
  • Dose conversions should be conservative and doses are usually rounded down (Note – check available strengths).
  • Adjust and monitor doses closely, extra care with: opioid toxicity; frail and elderly patients; renal or hepatic impairment.
  • Always prescribe an appropriate drug and dose for breakthrough pain:
    • 1/6th to 1/10th of the 24 hour regular opioid dose as required.

 

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Conversions from weak opioids to oral morphine
Weak opioid dose Equivalent oral morphine dose Conversion factor from weak oral opioid to morphine
Oral codeine or oral dihydrocodeine 240mg/24hrs ≈ Oral morphine 24mg/24hrs Divide by 10
Tramadol 400mg/24hrs* ≈ Oral morphine 40mg/24hrs Divide by 10
Buprenorphine
7-day Patch 5micrograms/hr**		 ≈ Oral morphine 12mg/24hrs

 

* Not generally recommended for use in palliative care.

** Note buprenorphine is measured in micrograms and morphine is measured in milligrams.

 

Conversions from oral strong opioids to other strong opioids
Oral morphine dose Equivalent opioid dose Conversion factor from oral morphine to other opioid
Morphine 10mg ≈ SC morphine 5mg Divide by 2
Morphine 10mg ≈ SC diamorphine 3mg Divide by 3
Morphine 10mg ≈ Oral oxycodone 5mg Divide by 2
Morphine 10mg ≈ SC oxycodone 2mg to 3mg Divide by 4
Morphine 30mg to 60mg ≈ Fentanyl patch
12 micrograms/hour		 Refer to: Fentanyl
Morphine 60mg to 90mg ≈ Fentanyl patch
25 micrograms/hour		 Refer to: Fentanyl
Morphine 30mg ≈ SC alfentanil 1mg* Divide by 30
Refer to: Alfentanil
Morphine 10mg ≈ Oral hydromorphone 1.3mg Divide by 5 to 7.5
Morphine 15mg ≈ SC hydromorphone 1mg* Divide by 10
Oral oxycodone dose Equivalent opioid dose Conversion factor from oral oxycodone to other opioid
Oxycodone 5mg ≈ SC oxycodone 2mg to 3mg Divide by 2
Oxycodone 5mg ≈Oral morphine 10mg Multiply by 2
Oxycodone 5mg ≈ SC diamorphine 3mg Divide by 1.5
Oxycodone 15mg to 30mg ≈ Fentanyl patch 12 micrograms/hour Refer to: Fentanyl
Oxycodone 30mg to 45mg ≈ Fentanyl patch
25 micrograms/hour		 Refer to: Fentanyl
Oxycodone 15mg ≈ SC alfentanil 1mg* Divide by 15
Oxycodone 5mg ≈ oral hydromorphone 1.3mg* Divide by 4

*Use only with specialist palliative care input

Dose Conversions

A guide to dose conversions FROM morphine TO second-line opioid analgesics used for moderate to severe pain

Use the tables above as a guide. The doses are approximate (≈) and not exact equivalent doses. Breakthrough opioid doses are based on a calculation of 1/6th of the daily dose - these doses may be adjusted up or down to avoid the use of decimal points and to allow a practical dose to be administered. Some patients may require a smaller 4-hour breakthrough dose of 1/10th of the daily dose. Initiate dose with caution depending on clinical condition and judgement.

  • Opioid bioavailability (particularly for oral morphine) and response are highly variable.
  • It is important to exercise caution when switching opioids. Start low and titrate gradually.
  • Always prescribe an appropriate drug and dose for breakthrough pain: 1/6th to 1/10th of the 24 hour regular opioid dose as required.
  • Opioid conversions and ratios may vary depending on the resource used. The conversions used in these guidelines are based on consensus of use across Scotland and reference sources.
  • Consider reducing the dose by up to 30% and re-titrating:
    • when changing opioid because of differences in pharmacokinetics and pharmacodynamics, including incomplete cross tolerance
    • if the patient is opioid toxic, frail or elderly.
  • Check the information about individual drugs if the patient has renal or liver impairment.
  • Particular care is needed when changing between opioids at higher doses or when the dose of the first opioid has been rapidly increased as these patients are at greater risk of adverse effects.
  • Morphine and oxycodone doses can be measured accurately in 1mg dose increments. Decimal places are not recommended.
  • Fentanyl: Refer to Fentanyl Patches information sheet for dose conversions.
  • Alfentanil: Refer to Alfentanil information sheet for dose conversions.
  • The effective sublingual/buccal dose of Fentanyl cannot be reliably predicted from the background maintenance opioid dose and individual titration for a patient is required, always starting at the lowest dose.
  • Monitor the patient carefully. If in doubt, seek advice.

Dose advice for "as required" prescriptions

  • Patients on a regular opioid will require an opioid prescribed as required for breakthrough pain. An appropriate as required dose is typically 1/6th to 1/10th of the regular opioid dose.
  • The as required dose is usually increased appropriately when the dose of regular opioid is increased.
  • For most as required opioids a prescribing interval equivalent to the duration of expected onset of action for the route administered is permitted, particularly if pain is severe to allow for dose titration whilst monitoring for toxicity. The prescription should also identify that if 3 or more doses have been given within 4 hours with little or no benefit urgent advice or review should be sought.  If more than 6 doses are required in 24 hours advice or review should be requested.
  • Refer to Care in the last days of life guideline.
  • Seek specialist advice when prescribing rapid acting fentanyl preparations or refer to the medicine information sheet if familiar with the product - Fentanyl sublingual (Abstral)®, Fentanyl buccal (Effentora)® and Fentanyl nasal spray (PecFent)®.