Morphine Milligram Equivalents (MME) – Clinical Guidance

Standard Opioid Conversion Factors

*These factors translate the daily dose of each opioid into an equivalent amount of morphine for risk‑assessment purposes. 1

Calculating Daily MME

*Example calculations illustrate the method: a daily total of 20 mg hydrocodone (conversion factor 1.0) equals 20 MME/day; a daily total of 20 mg oxycodone (conversion factor 1.5) equals 30 MME/day. The same calculation approach applies to any opioid regimen. 1

Dosing Thresholds for Safety

50 MME/Day Threshold

• Clinicians should pause and reassess the individual benefit‑risk balance before increasing a patient’s total opioid dose to ≥ 50 MME/day.
• Most patients do not achieve additional pain or functional improvement at this level, while the risk of adverse outcomes rises progressively.
• When the threshold is reached, extra precautions such as more frequent follow‑up visits and offering naloxone are recommended.
• Any dose escalation should be made in the smallest practical increments. 1

90 MME/Day Threshold

• Increasing a patient’s opioid dose to ≥ 90 MME/day should be avoided unless the clinician can clearly justify the decision based on diagnosis, measurable incremental benefits in pain or function, availability of alternative therapies, and specialist input. 1

Initiating Opioid Therapy

• For opioid‑naïve individuals, start with the lowest effective dose, generally 20–30 MME/day, and titrate upward only as needed and justified. 1

Opioid Rotation (Switching Between Opioids)

• MME conversion factors are intended solely for risk assessment and must not be used to determine the dose of a new opioid when rotating. 1
• Because conversion factors are estimates and cannot capture individual genetic or pharmacokinetic variability, the calculated equianalgesic dose should be reduced by 25–50 % to account for incomplete cross‑tolerance.
• Recommended protocol:

Special Considerations for Specific Opioids

Methadone

• Methadone has a long, variable half‑life; its peak respiratory depressant effect occurs later and persists longer than its analgesic peak, necessitating heightened caution during dose conversion. 1

Transdermal Fentanyl

• Fentanyl patches are dosed in µg/hr, not mg/day.
• Patch absorption can be markedly increased by heat and other external factors, so extra vigilance is required when estimating MME for transdermal fentanyl. 1

Buprenorphine for Pain

• Buprenorphine products used for pain are excluded from standard MME tables because their partial μ‑receptor agonism produces a ceiling effect that differs from full agonists. 1

Purpose and Limitations of MME

• The CDC developed these conversion factors primarily to:
• These recommendations serve as guideposts rather than rigid standards; clinicians should integrate them with individualized clinical judgment and patient‑centered decision‑making. 1

Opioid Dosage Recommendations

Key Principles

• The Centers for Disease Control and Prevention (CDC) recommends clinicians carefully reassess benefits and risks when considering increasing opioid dosage to ≥50 MME per day, and should avoid increasing dosage to ≥90 MME per day or carefully justify such decisions based on individualized assessment of benefits and risks 2, 3, 4
• Before reaching 50 MME/day, clinicians must pause and carefully reassess whether opioids are meeting the patient's treatment goals 2, 3
• At or above 50 MME/day, implement additional precautions including increased frequency of follow-up and considering offering naloxone 2, 5
• Many patients do not experience benefit in pain or function from increasing opioid dosages to ≥50 MME/day but are exposed to progressive increases in risk as dosage increases 4
• Clinicians should avoid increasing dosages to ≥90 MME/day or must carefully justify such decisions based on diagnosis, incremental benefits for pain and function relative to harms, other treatments and effectiveness, and recommendations from pain specialists 2, 3
• If patients do not experience improvement in pain and function at ≥90 MME/day, or if there are escalating dosage requirements, clinicians should discuss other approaches to pain management and consider tapering 2, 3
• Established patients already prescribed high dosages (≥90 MME/day) should be offered the opportunity to reevaluate their continued use in light of evidence regarding the association of opioid dosage and overdose risk 2, 3

Starting Opioid Therapy

• Clinicians should start opioids at the lowest effective dosage, typically equivalent to 20-30 MME/day for opioid-naïve patients 6
• Use immediate-release opioids instead of extended-release/long-acting formulations when initiating therapy 2, 5
• Increase dosage by the smallest practical amount when necessary 2, 3
• Use caution when prescribing opioids at any dosage 2, 3, 4

MME Conversion Factors

• To calculate total daily MME, multiply the daily dose of each opioid by its conversion factor 7, 8, 4
• Morphine: 1.0 4
• Oxycodone: 1.5 9
• Hydrocodone: 1.0 4
• Hydromorphone: 4.0 (2016) or 5.0 (2022) 4
• Fentanyl transdermal (mcg/hr): 2.4 4
• Codeine: 0.15 8
• Methadone: 4.0-12.0 (dose-dependent) or 4.7 (2022) 4
• Tramadol: 0.2 4
• Tapentadol: 0.4 7

Critical Conversion Cautions

• Do not use calculated MME doses to determine doses when converting between opioids—the new opioid should be dosed substantially lower than the calculated MME to avoid overdose due to incomplete cross-tolerance 7, 8, 5, 9
• Methadone requires particular caution due to its long and variable half-life, with peak respiratory depressant effect occurring later and lasting longer than peak analgesic effect 7, 8, 4
• Transdermal fentanyl is dosed in mcg/hr (not mg/day) and its absorption is affected by heat and other factors 7, 8, 4
• IV opioids are 2-3 times more potent than oral equivalents due to avoidance of first-pass metabolism 9
• The 90 MME/day threshold is not intended as an inflexible standard but as a guidepost to inform clinician-patient decision-making 4
• Concurrent benzodiazepine use significantly increases overdose risk at any opioid dose 5

Hydrocodone Dosing Recommendations and Acetaminophen Safety

Dosage Recommendations for Opioid‑Naïve Adults

• The recommended initial dosing range for hydrocodone in opioid‑naïve adults is 5–15 mg every 4–6 hours as needed, placing a 10 mg tablet in the middle of the therapeutic window (guideline recommendation) 10.

Acetaminophen Dose Monitoring

• Although the 325 mg acetaminophen component of a hydrocodone/acetaminophen tablet does not contribute to morphine milligram equivalents, clinicians must track it separately to ensure the maximum daily acetaminophen limit of 4 g is not exceeded (risk‑management guidance) 10.