Total daily opioid load using CDC conversion factors.
Add each opioid with total daily mg.
Enter values to see the result.
Formula: MME/day = Σ (daily mg × CDC conversion factor)
CDC guideline thresholds (50 MME caution, 90 MME high-risk) are advisory. Methadone has variable conversion; consult specialist.
Equianalgesic dosing refers to the doses of different opioid analgesics that produce approximately equivalent analgesic effects — in other words, doses that relieve pain to the same degree. Equianalgesic tables are essential tools in pain management for clinicians who need to convert a patient from one opioid to another (a process called opioid rotation or opioid switching) or who are calculating total opioid burden across multiple concurrent prescriptions.
Morphine has served as the reference standard for opioid comparison since the development of the first equianalgesic tables in the 1960s and 1970s, primarily because it was the most extensively studied opioid at the time. The choice of morphine as the reference is somewhat arbitrary — any opioid could have served this function — but the convention has persisted and morphine milligram equivalents (MME) have become the universal currency of opioid dose comparison. All other opioids are expressed as a ratio relative to oral morphine, with a morphine conversion factor of 1.0 by definition.
The clinical importance of equianalgesic conversion cannot be overstated. Opioids differ markedly in potency (the dose required to achieve a given effect), pharmacokinetics (absorption, distribution, metabolism, and elimination), receptor binding profiles, and side effect burden. Ignoring potency differences when switching opioids — for example, assuming that 10 mg of oxycodone equals 10 mg of morphine when oxycodone is approximately 1.5 times more potent — has led to preventable overdoses and deaths. Conversely, underdosing during opioid rotation due to excessive dose reduction, while safer, may leave patients in inadequately controlled pain.
Incomplete cross-tolerance is a critically important pharmacological principle underlying opioid rotation. When a patient has been on one opioid for an extended period, they develop tolerance specifically to that opioid at its receptor binding sites. However, switching to a different opioid — even at a mathematically equianalgesic dose — exposes the patient to a medicine to which they may have less tolerance, because opioid tolerance is not fully cross-reactive between all opioid agonists. This phenomenon of incomplete cross-tolerance is the primary rationale for the standard clinical practice of reducing the calculated equianalgesic dose by 25-50% when rotating opioids, to protect against unintended overdose.
It is essential to understand that equianalgesic tables represent population-average data, not precise individual predictions. Significant inter-individual variation in opioid pharmacokinetics (driven by CYP2D6 polymorphisms, CYP3A4 inducers/inhibitors, renal and hepatic function differences, and opioid receptor genetic variants) means that equianalgesic estimates may not be accurate for any given patient. Clinical titration — starting with a conservative dose estimate and adjusting based on observed analgesic effect and side effects — is always necessary.
The concept of Morphine Milligram Equivalents (MME) — sometimes called Oral Morphine Equivalents (OME) or Morphine Equivalent Dose (MED) — was developed and standardized by the Centers for Disease Control and Prevention (CDC) as a tool for quantifying opioid prescribing burden in a standardized manner across different opioids and formulations. MME allows a clinician, pharmacist, payer, or regulator to express the total opioid load of a patient's prescription(s) in a single comparable number.
The calculation is straightforward: daily MME = daily dose in mg × CDC conversion factor. For a patient taking oxycodone 10 mg three times daily (30 mg/day) and hydrocodone 5 mg twice daily (10 mg/day): MME = (30 × 1.5) + (10 × 1.0) = 45 + 10 = 55 MME/day. This combined total represents the patient's total opioid burden expressed as its morphine equivalent.
The CDC Opioid Prescribing Guidelines (2016, updated 2022) identified two important MME thresholds based on epidemiological overdose risk data: 50 MME/day, at which the risk of opioid overdose begins to increase substantially, and 90 MME/day, above which the risk of overdose is substantially elevated (approximately twice the risk compared with lower doses). These thresholds generated significant discussion in the pain management community, as they were interpreted by some prescribers, insurers, and regulators as absolute prescribing limits — an interpretation explicitly rejected by the CDC in its 2022 guideline revision.
The 2022 CDC Clinical Practice Guideline revision was notably more nuanced than the 2016 version. The 2022 guidelines emphasize that 90 MME/day is not a hard prescribing limit, that clinical judgment and individualized patient assessment must always guide opioid prescribing, and that abrupt dose reductions or forced tapers in patients on stable long-term opioid therapy may cause harm (including patient abandonment, undertreated pain, and diversion to illicit opioids). The guidelines recommend working collaboratively with patients to optimize opioid therapy, considering dose reduction when risks outweigh benefits, but never mechanically applying an MME threshold as an absolute contraindication.
For fentanyl transdermal patches, the conversion to MME is particularly prone to misunderstanding. Fentanyl patches are labeled in mcg/hour (e.g., 25 mcg/hr). The CDC conversion factor for transdermal fentanyl is 2.4 MME per mcg/hr. Therefore, a fentanyl 25 mcg/hr patch = 25 × 2.4 = 60 MME/day. The conversion factor for oral transmucosal fentanyl products (lozenges, buccal tablets, sublingual spray) uses a different conversion (approximately 0.13 MME per mcg of labeled dose) reflecting the different bioavailability and intended use pattern of these products.
Buprenorphine presents a unique challenge for MME calculation. As a partial agonist at the mu-opioid receptor and an antagonist at the kappa receptor, buprenorphine has a ceiling effect for respiratory depression at standard doses, meaning standard MME conversion tables (which assume full agonist activity and proportional respiratory depression risk) do not accurately represent buprenorphine's overdose risk profile. The CDC assigns buprenorphine a conversion factor of 10 MME per 1 mg of sublingual buprenorphine, but this conversion is highly contested and clinicians should exercise significant caution in applying it.
| Opioid | Brand Names | Route | CDC MME Factor | Example |
|---|---|---|---|---|
| Morphine (oral) | MS Contin, Roxanol | PO | 1.0 | 30 mg/day = 30 MME |
| Morphine (IV/IM) | Duramorph | IV/IM | 3.0 | 10 mg IV = 30 MME |
| Oxycodone | OxyContin, Percocet | PO | 1.5 | 20 mg/day = 30 MME |
| Hydrocodone | Vicodin, Norco, Zohydro | PO | 1.0 | 30 mg/day = 30 MME |
| Hydromorphone (oral) | Dilaudid | PO | 4.0 | 7.5 mg/day = 30 MME |
| Hydromorphone (IV) | Dilaudid IV | IV | 20.0 | 1.5 mg IV = 30 MME |
| Fentanyl (transdermal) | Duragesic patch | TD | 2.4 / mcg/hr | 25 mcg/hr = 60 MME/day |
| Fentanyl (IV) | Sublimaze | IV | 100 / mcg | See note |
| Oxymorphone (oral) | Opana | PO | 3.0 | 10 mg/day = 30 MME |
| Codeine | Tylenol #3/#4 | PO | 0.15 | 200 mg/day = 30 MME |
| Tramadol | Ultram, ConZip | PO | 0.1 | 300 mg/day = 30 MME |
| Tapentadol | Nucynta | PO | 0.4 | 75 mg/day = 30 MME |
| Methadone 1–20 mg/day | Dolophine, Methadose | PO | 4.0 | Complex — see text |
| Methadone 21–40 mg/day | Dolophine | PO | 8.0 | Complex — see text |
| Methadone 41–60 mg/day | Dolophine | PO | 10.0 | Complex — see text |
| Methadone >60 mg/day | Dolophine | PO | 12.0 | Complex — see text |
| Buprenorphine (SL) | Suboxone, Subutex | SL | 10.0 (contested) | See note |
Sources: CDC Clinical Practice Guideline 2022. Methadone MME is dose-dependent due to nonlinear pharmacokinetics. Always verify with a clinical pharmacist for methadone conversions.
Opioid rotation (also called opioid switching or opioid substitution) is the clinical practice of changing a patient from one opioid to another. Indications for rotation include: inadequate analgesia despite dose escalation on the current opioid; intolerable adverse effects (opioid-induced neurotoxicity, severe constipation, pruritus, nausea, or myoclonus from accumulation of active metabolites); development of rapid tolerance; and the need for a different route of administration due to changes in the patient's clinical status (e.g., inability to swallow).
The most important practical rule of opioid rotation is the dose reduction principle based on incomplete cross-tolerance. Standard clinical practice mandates reducing the calculated equianalgesic dose by 25-50% when converting from one full opioid agonist to another. The standard reduction is 25-30% in patients with well-controlled pain switching primarily due to side effects, and 50% in patients with more complex situations or less predictable pharmacology. After completing the rotation at the reduced dose, the opioid is titrated upward based on analgesic effect and tolerability.
Exceptions to the dose reduction rule exist. When rotating to methadone — a medicine with uniquely complex and nonlinear pharmacokinetics — substantially greater dose reductions (75-90%) are typically recommended and expert consultation is strongly advised. Methadone's equianalgesic potency increases disproportionately at higher morphine equivalent doses, meaning a patient on 200 MME/day of morphine requires a far lower percentage of that calculated methadone equivalent than a patient on 30 MME/day. Methadone also has a very long and unpredictable half-life (24-120 hours), QTc-prolonging effects, and significant medicine interaction potential, making rotation without specialist involvement high-risk.
The re-titration phase after opioid rotation requires close monitoring, typically with more frequent patient contact than routine opioid management. Patients should be counseled to contact their prescriber promptly if they experience breakthrough pain (suggesting underdosing) or signs of oversedation (suggesting overdosing): excessive drowsiness, difficulty being awakened, slurred speech, or slow/shallow breathing. Prescribing naloxone for patients undergoing opioid rotation is a recommended safety measure, and patients and caregivers should receive counseling on its use.
The 2022 CDC Clinical Practice Guideline for Prescribing Opioids replaced the controversial 2016 guidelines with a more nuanced framework emphasizing patient-centered care, clinical judgment, and avoidance of the harms associated with rigid dose limits. The 2022 guidelines were developed in response to evidence that overly rigid interpretation of the 2016 guidelines — particularly the 90 MME/day threshold — led to abrupt opioid dose reductions or discontinuations in patients on stable long-term therapy, causing preventable harm including undertreated pain, opioid withdrawal, and in some cases, transition to illicit opioid use.
Key recommendations of the 2022 guidelines include: (1) Non-opioid therapies (physical therapy, cognitive behavioral therapy, acetaminophen, NSAIDs, antidepressants, anticonvulsants, topical agents) are preferred as first-line treatment for chronic pain conditions; (2) When opioids are used for acute pain, the lowest effective dose for the shortest duration consistent with the severity of the pain should be prescribed; (3) When prescribing for subacute or chronic pain, clinicians should carefully weigh benefits and risks, use risk assessment tools, and establish treatment goals with patients; (4) The 90 MME/day threshold should not be a mandatory ceiling but a signal to reassess therapy carefully.
The 2022 guidelines also address the critical issue of opioid use disorder (OUD) treatment, emphasizing that medications for OUD — buprenorphine and methadone — should be offered to all patients with OUD and that prescribers should ensure these patients have access to treatment. Naloxone co-prescribing is recommended for patients at elevated overdose risk, including those on higher doses, those using concurrent benzodiazepines, and those with a history of OUD or prior overdose.
Transdermal fentanyl (Duragesic and generics) is a highly potent opioid delivery system that releases fentanyl continuously through skin absorption at a rate measured in micrograms per hour (mcg/hr). Available patch strengths are 12.5, 25, 37.5, 50, 62.5, 75, 87.5, and 100 mcg/hr. Patches are typically changed every 72 hours (some patients require 48-hour changes due to faster metabolism).
Converting to MME: Using the CDC conversion factor of 2.4 MME per mcg/hr patch dose, a 25 mcg/hr fentanyl patch delivers 25 × 2.4 = 60 MME/day; a 50 mcg/hr patch = 120 MME/day; a 100 mcg/hr patch = 240 MME/day. These are substantial daily opioid loads that exceed the CDC 90 MME threshold even at the 50 mcg/hr patch size.
When converting from oral opioids to a fentanyl patch, the standard approach is to calculate the patient's current total daily MME and then identify the fentanyl patch dose that approximates 50-60% of that MME (applying the incomplete cross-tolerance dose reduction). For example: a patient on oral morphine 120 mg/day (120 MME). The estimated equianalgesic fentanyl dose would be 120 MME ÷ 2.4 = 50 mcg/hr. After applying a 25% reduction: 37.5 mcg/hr patch is appropriate, with rescue medication available for breakthrough pain during the titration phase.
Important pharmacokinetic considerations: Fentanyl patches do not reach steady-state plasma concentrations until 12-24 hours after initial application, meaning analgesic effect is delayed. Patients transitioning from short-acting opioids should have overlap coverage for the first 12 hours. Conversely, when a patch is removed, fentanyl continues to be absorbed from the skin depot for 12-24 additional hours, meaning the full pharmacological effect persists well beyond patch removal — a critical consideration in managing overdose or toxicity.
Opioid dosing in older adults (age 65+) requires systematic dose reductions due to multiple pharmacokinetic and pharmacodynamic changes associated with aging. Standard guidance is to start at 25-50% of the typical adult dose and titrate more slowly. Reduced hepatic blood flow and CYP450 enzyme activity decrease opioid clearance; reduced renal function impairs elimination of active opioid metabolites; and reduced plasma protein binding increases free medicine fraction. Pharmacodynamically, elderly patients are more sensitive to opioid-induced respiratory depression, sedation, and falls due to age-related decreases in receptor reserve and impaired homeostatic compensation.
Renal impairment critically affects opioid management because many active opioid metabolites are renally eliminated and accumulate to toxic levels in renal failure. Morphine-6-glucuronide (M6G), the principal active metabolite of morphine, is more potent than morphine itself and accumulates dramatically in renal failure, causing prolonged and severe opioid toxicity. Morphine should generally be avoided in patients with significant renal impairment (GFR < 30 mL/min). Preferred alternatives include hydromorphone (though its metabolite hydromorphone-3-glucuronide also requires monitoring), fentanyl (least dependent on renal elimination), and buprenorphine (minimal renal adjustment required).
Most opioids undergo extensive hepatic metabolism, and significant hepatic impairment (Child-Pugh class B or C) reduces opioid clearance and prolongs half-life, necessitating dose reductions and extended dosing intervals. Codeine is particularly problematic in severe liver disease — it requires hepatic CYP2D6-mediated conversion to morphine for analgesic activity, and this conversion is impaired in severe hepatic dysfunction. Tramadol similarly requires hepatic conversion to its active O-desmethyl metabolite. Opioid-naive patients with significant hepatic impairment should begin at the lowest possible dose and be monitored closely.
No. The CDC has explicitly clarified in its 2022 guidelines that 90 MME/day is not a mandatory ceiling or legal prescribing limit. It is an epidemiological threshold above which overdose risk is substantially elevated, intended to prompt careful clinical reassessment of opioid therapy — not to trigger automatic dose reductions or prescription refusals. Some states and insurers have implemented policies around this threshold, but the CDC's intent is clinical guidance, not regulation. Patients on stable, beneficial long-term opioid therapy above 90 MME should not have doses abruptly reduced purely because of an MME threshold.
Methadone conversion is uniquely complex because methadone's equianalgesic potency relative to morphine increases non-linearly as the daily dose increases. The CDC uses dose-dependent conversion factors: 4 MME/mg for methadone 1-20 mg/day, 8 MME/mg for 21-40 mg/day, 10 MME/mg for 41-60 mg/day, and 12 MME/mg for doses above 60 mg/day. Due to methadone's complex pharmacokinetics (very long and variable half-life, significant medicine interactions, and QTc-prolonging potential), any methadone conversion — whether calculating MME or switching from/to methadone — should involve a clinical pharmacist with pain management or addiction medicine expertise.
Buprenorphine is a partial opioid agonist with a ceiling effect for respiratory depression at doses used clinically for both pain management and opioid use disorder treatment. Standard MME conversion factors do not accurately reflect buprenorphine's overdose risk, because the proportional respiratory depression risk that underpins the MME framework does not apply to a partial agonist with a safety ceiling. The CDC conversion factor of 10 MME per 1 mg sublingual buprenorphine is widely considered an overestimate of buprenorphine's overdose risk. Clinicians managing patients on buprenorphine products (Suboxone, Belbuca, Butrans) should consult addiction medicine or pain specialists rather than relying on standard MME calculations.
The CDC conversion factors and the 90 MME threshold were derived from adult population data and are not validated for pediatric use. Pediatric opioid dosing requires weight-based mg/kg calculations with age-appropriate maximum doses, and equianalgesic conversions in children are generally extrapolated from adult data with appropriate caution. Pediatric pain management, particularly for cancer pain or chronic conditions, should involve a pediatric pain specialist. This calculator is intended for adult use only.
Yes, significantly. Parenteral (IV or IM) opioids are more bioavailable than oral preparations of the same medicine, because oral opioids undergo first-pass hepatic metabolism that reduces the fraction reaching systemic circulation. Morphine IV is approximately 3 times more potent mg-for-mg than oral morphine (oral bioavailability ~30%). The conversion table accounts for route: oral morphine has a factor of 1.0, while IV morphine has a factor of approximately 3.0. When calculating MME for patients receiving both oral and parenteral opioids (as in post-operative or palliative care settings), applying the correct route-specific conversion factor is essential.
Opioid-induced hyperalgesia (OIH) is a paradoxical phenomenon in which long-term opioid use actually increases pain sensitivity rather than reducing it. Patients with OIH experience worsening pain despite escalating opioid doses, and the pain may become more diffuse and less localized than the original complaint. OIH is thought to involve central sensitization mediated by NMDA receptor activation and neuroplastic changes. It is most documented with high-dose, long-term opioid therapy. Recognizing OIH is clinically important because the appropriate response is opioid dose reduction or rotation (not further escalation), potentially with addition of NMDA antagonists such as low-dose ketamine or methadone.
CYP2D6 is the liver enzyme responsible for converting codeine to morphine (and tramadol to its active O-desmethyl metabolite). Genetic polymorphisms in CYP2D6 create four metabolizer phenotypes: poor metabolizers (2D6 deficient) cannot convert codeine to morphine and experience no analgesic effect; ultrarapid metabolizers (multiple gene copies) convert codeine extremely rapidly to morphine, achieving toxic morphine levels from standard codeine doses — a risk that has caused deaths in ultrarapid metabolizer breastfeeding mothers and their infants. Pharmacogenomic testing for CYP2D6 is increasingly available and can guide opioid selection. Codeine is contraindicated in ultrarapid metabolizers and in breastfeeding mothers.
Naloxone (Narcan) is a pure opioid receptor antagonist that rapidly reverses opioid-induced respiratory depression and can be life-saving in overdose. The CDC 2022 guidelines recommend co-prescribing naloxone for patients on ≥50 MME/day, patients on concurrent opioids and benzodiazepines, patients with a history of OUD, and patients who have previously experienced overdose. Naloxone is available as nasal spray (Narcan 4 mg/spray), auto-injector (Evzio), and parenteral formulations. Patient and caregiver education on recognizing signs of opioid overdose (unresponsiveness, slow or absent breathing, blue lips) and using naloxone is an essential component of high-dose opioid prescribing.
Equianalgesic tables represent population averages derived from single-dose studies in opioid-naive patients, and their accuracy for any individual patient — particularly those on chronic opioid therapy — is limited. Studies have shown wide inter-individual variation in opioid pharmacokinetics and pharmacodynamics, meaning that the actual equianalgesic dose for a given patient may deviate substantially from the table-derived estimate. Equianalgesic tables are best understood as starting-point estimates, not precise prescriptions. Clinical titration, frequent reassessment, and patient education about breakthrough pain management and overdose recognition are essential complements to table-based dose calculations.
The combination of opioids with benzodiazepines (alprazolam, clonazepam, diazepam, lorazepam) or other CNS depressants dramatically increases overdose risk through synergistic respiratory depression. Data from the FDA and CDC show that opioid overdose deaths involving benzodiazepines are dramatically overrepresented relative to their prevalence in opioid prescriptions. Other dangerous combinations include opioids with muscle relaxants (cyclobenzaprine, carisoprodol), gabapentinoids (gabapentin, pregabalin — which have significant respiratory depressant effects at higher doses), and alcohol. The FDA has issued black box warnings on all opioid labeling about the risk of combining opioids with benzodiazepines.
The opioid crisis represents one of the most significant public health challenges of recent decades. In the United States alone, opioid-related overdose deaths have exceeded 80,000 annually, with prescription opioids contributing significantly to this mortality. The CDC and other health authorities have responded by emphasizing risk stratification through Morphine Milligram Equivalent (MME) calculations as a cornerstone of safer prescribing practices.
The MME concept allows clinicians to standardize and compare opioid doses across different medications. Each opioid has its own potency relative to morphine, and combinations of multiple opioids can dramatically increase total exposure. By converting all opioid doses to a common metric (oral morphine equivalents), clinicians can identify patients at elevated risk for overdose, withdrawal, and other complications.
Opioids exert their analgesic effects primarily through agonism at mu, kappa, and delta opioid receptors throughout the central and peripheral nervous systems. Different opioids have varying selectivity and intrinsic activity at these receptors, contributing to differences in efficacy and side effect profiles. The major opioid receptor effects include analgesia, respiratory depression, sedation, euphoria, miosis, constipation, and physical dependence.
The pharmacokinetics of opioids vary considerably. Short-acting opioids (immediate-release morphine, hydromorphone, oxycodone) have rapid onset and 3-4 hour duration, making them suitable for breakthrough pain or acute pain. Long-acting opioids (extended-release morphine, oxycodone ER, methadone) provide 8-24 hour analgesia for chronic pain management. Fentanyl transdermal patches deliver continuous medication for 72 hours through skin absorption. Each formulation has different bioavailability, peak effects, and elimination characteristics affecting MME calculations.
The CDC's 2022 Clinical Practice Guideline for Prescribing Opioids for Pain provides evidence-based recommendations that have transformed prescribing practices:
Standard MME conversion factors used in clinical practice:
Methadone presents particular challenges in MME conversion because its conversion ratio increases dramatically with dose. The CDC recommends specific multipliers based on daily methadone dose, ranging from 4× for 1-20 mg/day to 12× for 61-80 mg/day or higher. Methadone's long half-life (15-60 hours) and unpredictable individual metabolism make it particularly dangerous when transitioning between opioids.
Research has established clear dose-response relationships between opioid dose and overdose risk:
Studies have demonstrated approximately 2-fold higher overdose risk at 20-49 MME/day and 9-fold higher risk at ≥100 MME/day compared with low-dose users. However, dose-related risk varies among individuals based on other risk factors including concomitant benzodiazepine use, alcohol consumption, sleep apnea, mental health conditions, and overall health status.
For patients on high-dose chronic opioid therapy who require dose reduction, tapering must be done carefully to minimize withdrawal and maintain pain control. Rapid tapers can cause severe withdrawal symptoms, worsening pain, mental health deterioration, and increased risk of suicide or transition to illicit opioids. The current CDC and other authoritative guidance emphasizes:
Naloxone is an opioid receptor antagonist that rapidly reverses opioid overdose. It is available as intranasal spray (Narcan, generic naloxone nasal spray) and injectable formulations. Naloxone should be co-prescribed with opioids in many situations:
Naloxone administration is the immediate response to suspected opioid overdose. Bystanders should call emergency services, administer naloxone (intranasal spray or injection), and perform rescue breathing if needed. Naloxone has minimal side effects in non-opioid users and is safe to administer when overdose is suspected.
Elderly Patients: Older adults are particularly vulnerable to opioid-related complications including falls, fractures, cognitive impairment, and constipation. Lower starting doses (often 50% of usual adult dose) and slower titration are recommended. Drug interactions are more common due to polypharmacy. Long-acting opioids carry particular risk in this population.
Pediatric Patients: Opioid use in children requires specialized expertise. Weight-based dosing, age-appropriate formulations, and close monitoring are essential. The risks of opioid use disorder are particularly concerning in adolescents and young adults.
Pregnant Women: Opioid use during pregnancy can cause neonatal opioid withdrawal syndrome (NOWS) in newborns. Women receiving long-term opioid therapy who become pregnant should not abruptly discontinue (withdrawal can harm the fetus); rather, careful continuation with multidisciplinary care is recommended. Opioid use disorder during pregnancy is treated with methadone or buprenorphine maintenance.
Patients with Substance Use Disorders: Individuals with history of opioid or other substance use disorder require particularly careful evaluation before opioid prescription. When opioids are necessary, treatments should be limited in duration, closely monitored, and combined with substance use treatment when applicable.
Comprehensive pain management increasingly emphasizes multimodal, non-opioid approaches: