Key Points
Use opioid equivalency tools when calculating morphine milligram equivalents (MME) or converting btwn opioid therapies. Conversion factors may differ btwn tools below.
For assessing dose-related risk of opioid-induced morbidity & mortality (such as overdose risk): Use MME Conversion Factors to calculate MME/day. For clinical use converting btwn opioid therapies: Use Opioid Dose Conversion Tools. Equianalgesic dose estimates do not account for pt variables (genetics, organ fxn, PK, DDIs, tolerance); refer to monograph & mfr PI for full prescribing info.
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Clinical considerations1,2 - MME/day is one element of opioid-related risk assessment; consider additional risk factors3 when assessing risk
- Do not use MME conversion factors to convert from one opioid to another
- Conversion factors apply to oral administration, unless otherwise specified
MME Conversion Factors Table Footnotes 1 CDC 2021. National Center for Injury Prevention and Control. Calculating Total Daily Dose of Opioids for Safer Dosage. Last updated 2/17/21. Last accessed 5/26/23
2 CMS 2020. Centers for Medicare & Medicaid Services. Opioid Oral Morphine Milligram Equivalent (MME) Conversion Factors. Last updated 1/1/20. Last accessed 8/13/21
3 UW 2019. Six Building Blocks: Risk Stratification and Opioid Prescribing. Version 2019.07.03. Family Medicine. University of Washington, Department of Family Medicine. Improving Opioid Care. Last updated 7/3/19. Last accessed 3/1/21 -
Opioid-Dose Conversion Tools
Clinical considerations1 - Values in table do not account for effects of single vs repetitive dosing
- Consider decreasing initial dose of new opioid by 25%-50% to account for incomplete cross-tolerance2
Equianalgesic dosing table3,4 Footnotes 1 Additional conversion info provided separately.
2 McPherson ML. Demystifying Opioid Conversion Calculations: A Guide for Effective Dosing. 2nd ed. American Society of Health-System Pharmacists; 2019.
3 NCCN 2019. Swarm RA, et al. Adult Cancer Pain, Version 3.2019, NCCN Clinical Practice Guidelines in Oncology. J Natl Compr Canc Netw. 2019. Aug1;17(8):977-1007. Free full-text article at JNCCN
4 Prescribing information.
5 Not currently available in U.S. fentanyl transdermal patch Clinical considerations1
- Table intended for conversion to fentanyl patch only
- For conversion from higher doses than those listed, see manufacturer prescribing info
- Manufacturer-recommended conversion method may be conservative2
Manufacturer-recommended conversion method Alternative conversion method2 - Calculate current equivalent oral morphine dose/day
- Use conversion factor of 0.5 to estimate initial mcg/h fentanyl transdermal dose (example: 50 mg oral morphine/day x0.5 = 25 mcg/h fentanyl transdermal)
- Round up or down to available patch strength depending on individual pt factors
- May also use to estimate dose if converting from fentanyl transdermal to a new opioid (example: 25 mcg/h fentanyl transdermal x2 = 50 mg oral morphine/day)
Footnotes 1 Reference: Fentanyl transdermal patch (SpecGx) 2020-05.
2 McPherson ML. Demystifying Opioid Conversion Calculations: A Guide for Effective Dosing. 2nd ed. American Society of Health-System Pharmacists; 2019.
Clinical considerations1 - May precipitate WD in pts on opioids; taper current opioid regimen to <30 mg/day for up to 7 days before converting to buprenorphine transdermal patch
- Manufacturer-conversion method may be conservative2
Manufacturer-recommended conversion method1 Footnotes 1 Reference: Butrans 2019-10.
2 McPherson ML. Demystifying Opioid Conversion Calculations: A Guide for Effective Dosing. 2nd ed. American Society of Health-System Pharmacists; 2019.
Clinical considerations1 - Buprenorphine may precipitate WD in pts on opioids; taper current opioid regimen to <30 mg/day days before converting to buprenorphine buccal film
Manufacturer-recommended conversion method1 Footnotes 1 Reference: Belbuca 2019-10. Clinical considerations | Manufacturer-recommended conversion method1,2 - Table intended for conversion to methadone only
- Conversion to/from methadone is an involved process as there’s wide interpatient variability & significant toxicity; consult w/ expert in methadone prescribing
Manufacturer-recommended conversion method to methadone1,2 Clinical considerations | Fudin equation model for methadone conversion3 - Complex equation developed to address pitfalls of existing conversion ratios; use online calculator preferably, otherwise use estimates in table below
- Conversion to/from methadone is an involved process as there's wide interpatient variability and significant toxicity; consult w/ expert in methadone prescribing
Fudin equation model for methadone conversion3 Footnotes 1 Reference: methadone tablets (SpecGx) 2020-02.
2 Reference: methadone solution (Atlantic) 2020-04.
3 Fudin J, et al. Mathematical Model for Methadone Conversion Examined. Pract Pain Manag. 2012. Sept;12(8):46-51. Free full-text PDF
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This epocrates resource is developed by our in-house team of pharmacist and physician editors.
Epocrates Guideline Synopsis Last Update:
May 26, 2023
Abbreviations
| MEDD |
morphine equivalent daily dose |
| MME |
morphine milligram equivalent |
| WD |
withdrawal |
