Codeine conversion reference
Check OpioidCalc's OME factors by route, then open the formulation-specific pharmacology, cautions and supporting sources.
Educational reference for qualified healthcare professionals. Conversion factors estimate oral morphine equivalent daily dose. They are not a recommended switching dose. Confirm the result with a current source and local guidance.
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Current OpioidCalc factors
Multiply the dose or delivery rate in the stated units by the factor to estimate mg oral morphine equivalent per day. These are the factors currently used by OpioidCalc. Methadone uses 4.7 when converting methadone to OME.
| Route | Input units | OME factor |
|---|---|---|
| Oral | mg/day | 0.1 |
| Parenteral | mg/day | 0.25 |
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Formulations and cautions
Choose a formulation to read its pharmacology, population, limitations and source references.
OralDefault in appImmediate-release tablet
App source review: 27 August 2026
View details and sources
Immediate-release tablet
App source review: 27 August 2026
View details and sources- Peak concentration or effect
- Peak concentration at 60 minutes
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Codeine sulfate tablet prescribing information12.3 Pharmacokinetics. United States. Source revised 16 January 2026. App review 27 August 2026. Regulatory product information.
- Elimination half-life
- Approximately 3 hours
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Codeine sulfate tablet prescribing information12.3 Pharmacokinetics. United States. Source revised 16 January 2026. App review 27 August 2026. Regulatory product information.
- Steady state
- Within 48 hours in the cited repeated-dose study
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Study regimen was 15 mg every four hours for five days; this is not a dosing recommendation.
- Codeine sulfate tablet prescribing information12.3 Pharmacokinetics. United States. Source revised 16 January 2026. App review 27 August 2026. Regulatory product information.
- Receptor activity
- Mu-opioid agonist with weaker affinity than morphine.
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Codeine sulfate tablet prescribing information12.1 Mechanism of Action. United States. Source revised 16 January 2026. App review 27 August 2026. Regulatory product information.
- Metabolism
- UGT2B7/UGT2B4 form codeine-6-glucuronide; CYP2D6 forms morphine; CYP3A4 forms norcodeine.
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Codeine sulfate tablet prescribing information12.3 Pharmacokinetics. United States. Source revised 16 January 2026. App review 27 August 2026. Regulatory product information.
- Active metabolites
- Morphine and morphine-6-glucuronide are analgesically active; human activity of codeine-6-glucuronide is uncertain.
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Codeine sulfate tablet prescribing information12.3 Pharmacokinetics. United States. Source revised 16 January 2026. App review 27 August 2026. Regulatory product information.
- Elimination
- About 90% is excreted renally, including about 10% unchanged codeine.
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Codeine sulfate tablet prescribing information12.3 Pharmacokinetics. United States. Source revised 16 January 2026. App review 27 August 2026. Regulatory product information.
- Renal impairment
- Reduced clearance and marked metabolite accumulation can occur in renal failure.
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Codeine sulfate tablet prescribing information8.6 Renal Impairment. United States. Source revised 16 January 2026. App review 27 August 2026. Regulatory product information.
- Hepatic impairment
- Pharmacokinetics in hepatic impairment have not been formally studied.
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Codeine sulfate tablet prescribing information8.7 Hepatic Impairment. United States. Source revised 16 January 2026. App review 27 August 2026. Regulatory product information.
OralImmediate-release oral solution
App source review: 27 August 2026
View details and sources
Immediate-release oral solution
App source review: 27 August 2026
View details and sources- Peak concentration or effect
- Peak analgesic effect within 2 hours
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Acetaminophen and codeine phosphate oral solution prescribing informationClinical Pharmacology. United States. Source revised 6 August 2026. App review 27 August 2026. Regulatory product information.
- Duration
- 4 to 6 hours
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Acetaminophen and codeine phosphate oral solution prescribing informationClinical Pharmacology. United States. Source revised 6 August 2026. App review 27 August 2026. Regulatory product information.
- Elimination half-life
- Approximately 2.9 hours
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Acetaminophen and codeine phosphate oral solution prescribing informationPharmacokinetics. United States. Source revised 6 August 2026. App review 27 August 2026. Regulatory product information.
- Formulation behaviour
- Evidence is from an acetaminophen/codeine combination oral solution.
Population: Adults described in the cited product information
Applicability: United States
- Limitation: Do not interpret this as a standalone codeine-solution label.
- Acetaminophen and codeine phosphate oral solution prescribing informationDescription and Clinical Pharmacology. United States. Source revised 6 August 2026. App review 27 August 2026. Regulatory product information.
ParenteralDefault in appSubcutaneous or intramuscular injection
App source review: 27 August 2026
View details and sources
Subcutaneous or intramuscular injection
App source review: 27 August 2026
View details and sources- Onset
- 10 to 30 minutes
Population: Adults described in the cited product information
Applicability: Canada (historical monograph)
- Limitation: Historical Canadian monograph; current Australian product information should replace it when a reliable public PI is available.
- Codeine phosphate injection product monographClinical Pharmacology. Canada (historical monograph). Source revised 4 November 2016. App review 27 August 2026. Regulatory product information.
- Peak concentration or effect
- 30 to 60 minutes
Population: Adults described in the cited product information
Applicability: Canada (historical monograph)
- Limitation: Historical Canadian monograph for subcutaneous or intramuscular injection.
- Codeine phosphate injection product monographClinical Pharmacology. Canada (historical monograph). Source revised 4 November 2016. App review 27 August 2026. Regulatory product information.
- Duration
- 4 to 6 hours
Population: Adults described in the cited product information
Applicability: Canada (historical monograph)
- Limitation: Historical Canadian monograph for subcutaneous or intramuscular injection.
- Codeine phosphate injection product monographClinical Pharmacology. Canada (historical monograph). Source revised 4 November 2016. App review 27 August 2026. Regulatory product information.
- Elimination half-life
- 3 to 4 hours; up to 19 hours in anephric patients
Population: Adults described in the cited product information
Applicability: Canada (historical monograph)
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Codeine phosphate injection product monographClinical Pharmacology. Canada (historical monograph). Source revised 4 November 2016. App review 27 August 2026. Regulatory product information.
- Metabolism
- Metabolism includes conversion to morphine and glucuronide metabolites.
Population: Adults described in the cited product information
Applicability: Canada (historical monograph)
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Codeine phosphate injection product monographClinical Pharmacology. Canada (historical monograph). Source revised 4 November 2016. App review 27 August 2026. Regulatory product information.
- Elimination
- Codeine and metabolites are eliminated primarily in urine.
Population: Adults described in the cited product information
Applicability: Canada (historical monograph)
- Limitation: Product-specific evidence; do not transfer to other formulations.
- Codeine phosphate injection product monographClinical Pharmacology. Canada (historical monograph). Source revised 4 November 2016. App review 27 August 2026. Regulatory product information.
ParenteralContinuous parenteral infusion
App source review: 27 August 2026
View details and sources
Continuous parenteral infusion
App source review: 27 August 2026
View details and sourcesSources used on this page
- Codeine sulfate tablet prescribing informationUnited States. Revision date 16 January 2026.
- Acetaminophen and codeine phosphate oral solution prescribing informationUnited States. Revision date 6 August 2026.
- Codeine phosphate injection product monographCanada (historical monograph). Revision date 4 November 2016.
Other medicine references
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