Opioid Equivalencies
Equianalgesic Dose Reference Table (relative to 10 mg IV Morphine)
⚠️ Critical Safety Note — Incomplete Cross-Tolerance: When switching between opioids, the calculated equianalgesic dose overestimates the required new dose. Reduce by 25–50% and titrate. Methadone requires a larger reduction (50–75%) due to its variable and prolonged half-life.
| Opioid | IV / IM (mg) | PO (mg) | IV:PO Ratio | Notes |
|---|---|---|---|---|
| Morphine | 10 | 30 | 1:3 | Standard reference opioid for all conversions |
| Hydromorphone | 1.5 | 7.5 | 1:5 | ~5–7x more potent than morphine IV |
| Oxycodone | — | 20 | N/A (PO only) | ~1.5x more potent than oral morphine |
| Hydrocodone | — | 30 | N/A (PO only) | Roughly equivalent to oral morphine mg-per-mg |
| Oxymorphone | 1 | 10 | 1:10 | ~3x more potent than oral morphine PO |
| Codeine | 130 | 200 | 1:1.5 | Prodrug; CYP2D6 dependent — poor metabolizers may have no effect; ultra-rapid metabolizers at risk of toxicity |
| Tramadol | 100 | 120 | ~1:1.2 | Weak opioid + SNRI activity; lowers seizure threshold; CYP2D6 dependent |
| Fentanyl IV | 0.1 (100 mcg) | — | N/A | ~100x more potent than IV morphine; short-acting; see patch conversion below |
| Methadone | Non-linear conversion — ratio is dose-dependent and highly variable. See dedicated methadone table below. | |||
| Buprenorphine (Partial Agonist) | Ceiling effect on respiratory depression; used for OUD and chronic pain. Requires specialized induction protocols — not a simple rotation. | |||
* All doses are approximate equianalgesic values for opioid-tolerant patients. For opioid-naive patients, use lower starting doses per prescribing information.
* IV/IM considered equivalent for most opioids. SC absorption may vary.
Fentanyl Transdermal Patch Conversion
Patch Conversion Rule: Fentanyl patches are appropriate only for opioid-tolerant patients (60 mg oral morphine/day equivalent for 1 week or more). Never use in opioid-naive patients.
| Oral Morphine Equivalent (OME/day) | Fentanyl Patch Dose |
|---|---|
| 60–134 mg/day | 25 mcg/hr |
| 135–224 mg/day | 50 mcg/hr |
| 225–314 mg/day | 75 mcg/hr |
| 315–404 mg/day | 100 mcg/hr |
* Change patch every 72 hours (some patients require every 48 hours due to pharmacokinetic variability).
* Peak effect: 12–24 hours after application. Residual drug released for ~17 hours after removal.
* Source: FDA-approved fentanyl transdermal prescribing information (Duragesic).
Methadone Conversion (Morphine OME to Methadone)
⚠️ High-Risk Conversion: Methadone has an extremely long and variable half-life (8–59 hours). Conversion ratios are non-linear and increase with higher prior opioid doses. QTc prolongation monitoring is essential. This conversion should only be performed by experienced clinicians.
| Prior Total Daily Oral Morphine Equivalent | Estimated Morphine : Methadone Ratio |
|---|---|
| <100 mg/day | 3:1 (3 mg morphine = 1 mg methadone) |
| 100–300 mg/day | 5:1 |
| 301–600 mg/day | 10:1 |
| 601–800 mg/day | 12:1 |
| 801–1000 mg/day | 15:1 |
| >1000 mg/day | 20:1 |
* Reduce calculated methadone dose by an additional 50–75% to account for incomplete cross-tolerance.
* Source: Adapted from Palliative Care Network of Wisconsin; and AAHPM guidance.
Oral Morphine Equivalent (OME) Conversion Factors
| Opioid | Route | Multiply Daily Dose By |
|---|---|---|
| Morphine | PO | × 1 |
| Morphine | IV / SC | × 3 |
| Hydrocodone | PO | × 1 |
| Codeine | PO | × 0.15 |
| Tramadol | PO | × 0.1–0.2 |
| Oxycodone | PO | × 1.5 |
| Oxymorphone | PO | × 3 |
| Hydromorphone | PO | × 4 |
| Hydromorphone | IV | × 20 |
| Fentanyl patch | Transdermal | × 2.4 (per mcg/hr) |
| Buprenorphine patch | Transdermal | × 12.6 (per mcg/hr) |
| Methadone | PO | Variable — see methadone table above |
* Conversion factors sourced from CDC Clinical Practice Guideline for Prescribing Opioids (2022) and Washington State AMDG opioid dosing guide.
Opioid Rotation — Step by Step
- Calculate the patient's total daily OME. Include all scheduled and PRN doses actually used.
- Use the equianalgesic table to find the equivalent dose of the new opioid.
- Reduce by 25–50% for incomplete cross-tolerance (50–75% for methadone).
- Divide into the appropriate dosing frequency for the new agent.
- Prescribe rescue doses at 10–15% of the total daily dose, q3–4h PRN.
- Reassess within 24–48 hours and titrate based on response and tolerability.
When Equivalency Tables Do Not Apply
- Opioid-naive patients: Tables are calibrated for tolerant patients — always start lower.
- Renal impairment: Morphine-6-glucuronide (active metabolite) accumulates — prefer hydromorphone or fentanyl.
- Hepatic impairment: Reduced first-pass metabolism increases bioavailability of oral opioids unpredictably.
- Elderly patients: Increased CNS sensitivity and reduced clearance — reduce doses further; avoid long-acting agents initially.
- Pediatric patients: Use weight-based dosing; these tables are for adults only.
- OUD / buprenorphine induction: Standard rotation tables do not apply — use specialized MOUD protocols.
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References
CDC Clinical Practice Guideline for Prescribing Opioids — United States, 2022. MMWR Recomm Rep. 2022;71(3):1–95.
Palliative Care Network of Wisconsin. Fast Facts: Equianalgesic Dosing of Opioids for Pain Management. 2023.
Washington State Agency Medical Directors' Group (AMDG). Interagency Guideline on Prescribing Opioids for Pain, 3rd ed. 2015.
Lexicomp Online; IBM Micromedex. Accessed April 2026.
Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
Individual US prescribing information for referenced opioids via DailyMed, NLM. Accessed April 2026.
This resource is intended for educational and reference purposes only and is not a substitute for clinical judgment. Institutional policies, protocols, and locally approved guidelines take precedence. Clinicians should consult their own institution's policies and applicable references before making therapeutic decisions. Version 1.0 — April 2026 — PharmGuides.