Oral Morphine Equivalent to 10 mg Oral Oxycodone
15 mg of oral morphine is equivalent to 10 mg of oral oxycodone, using the standard 1.5:1 conversion ratio (morphine:oxycodone).
Conversion Ratio
- The CDC recommends a conversion factor of 1.5 for oxycodone to morphine, meaning 10 mg of oxycodone equals 15 mg of oral morphine 1
- This 1.5:1 ratio is consistently supported across multiple guidelines for converting between these two opioids 1
- Some older literature suggests ratios ranging from 1:1 to 1:2 (oxycodone:morphine), but the 1.5:1 ratio represents current consensus for clinical practice 2, 3
Practical Application for Opioid-Naïve Patients
- For an opioid-naïve patient, if you're considering 10 mg oral oxycodone as a starting dose, the morphine equivalent would be 15 mg oral morphine 1
- However, NCCN guidelines recommend starting opioid-naïve patients with 5-15 mg of oral morphine (or equivalent) for pain intensity ≥4 4
- This means 10 mg oxycodone is at the upper end of appropriate initial dosing for opioid-naïve patients 4
Important Clinical Caveats
- When rotating between opioids (switching from one to another), you must reduce the calculated equianalgesic dose by 25-50% to account for incomplete cross-tolerance 1, 5
- This dose reduction does NOT apply when simply calculating equivalence for initial prescribing in opioid-naïve patients 1
- Individual patient variability exists due to differences in bioavailability (oxycodone 60-87% vs morphine lower bioavailability) and metabolism 2, 6
- Oxycodone may cause somewhat less nausea, hallucinations, and pruritus compared to morphine at equianalgesic doses 2