Oral Morphine Equivalent of 240mg Codeine Daily
240 mg of codeine daily is equivalent to approximately 24-36 mg of oral morphine daily.
Conversion Calculation
Using the most recent and authoritative guideline data, the conversion is straightforward:
- The 2025 NCCN Guidelines state that 200 mg of oral codeine equals 30 mg of oral morphine 1
- The 2022 CDC Guidelines provide a codeine conversion factor of 0.15 2
- The 2016 CDC Guidelines also use a 0.15 conversion factor 3
Mathematical Conversion:
- 240 mg codeine × 0.15 = 36 mg oral morphine equivalent
Alternatively, using the NCCN ratio:
- (240 mg ÷ 200 mg) × 30 mg = 36 mg oral morphine
However, older ESMO guidelines from 2005 suggest dihydrocodeine (a codeine analog) has a relative effectiveness of 0.17 compared to oral morphine 4, which would yield approximately 41 mg morphine equivalent. Given the consistency of the more recent guidelines (2016-2025), the 36 mg conversion is most reliable.
Important Clinical Considerations
Codeine's Variable Metabolism
Codeine requires CYP2D6-mediated conversion to morphine for analgesic effect, creating significant interindividual variability 5, 6:
- Poor metabolizers (CYP2D6 deficient): Codeine produces minimal to no morphine, resulting in little analgesic effect 5
- Extensive metabolizers: Approximately 10% of codeine is converted to morphine 7, 8, 9
- Ultra-rapid metabolizers: Risk of morphine toxicity from excessive conversion
Practical Implications for Conversion
When converting from codeine to morphine in a patient with normal hepatic and renal function:
- Start conservatively at 24-30 mg oral morphine daily (using a 0.10-0.125 conversion factor rather than 0.15)
- Titrate based on response over 24-48 hours
- Monitor closely for signs of under- or over-dosing, as the patient's actual codeine-to-morphine conversion efficiency is unknown
Why Conservative Dosing Matters
Research demonstrates that morphine accumulates with repeated dosing 8, and the actual morphine exposure from chronic codeine use may be higher than single-dose studies suggest. Additionally, codeine's analgesic efficacy is questionable - it performs poorly compared to other analgesics in controlled trials 6, suggesting some patients may have been receiving minimal effective analgesia and could be opioid-naive despite chronic codeine use.
Dosing Schedule
Divide the total daily morphine dose into immediate-release formulations given every 4 hours 10, 1:
- For 24-30 mg daily: 4-5 mg every 4 hours
- For 36 mg daily: 6 mg every 4 hours
- Provide rescue doses (10-15% of total daily dose) for breakthrough pain 11, 1
Renal and Hepatic Function Caveat
The question specifies normal renal and hepatic function, but both codeine and morphine require dose reduction if function is impaired 10, 11, 12. Morphine-6-glucuronide and morphine-3-glucuronide accumulate in renal failure 12, while codeine metabolism is impaired in hepatic dysfunction.