Tramadol to Morphine: how to convert safely

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Worked example

1. Total the 24-hour tramadol dose — say 200 mg/day oral.
2. Convert to morphine equivalents: 200 mg × 0.1 = 20 mg MME/day.
3. Convert to morphine: 20 ÷ 1 = 20 mg/day.
4. Apply a 25–50% cross-tolerance reduction: start near 15 mg/day or lower, divided by the dosing interval, with breakthrough doses available.

Try it with your patient's numbers

Cautions specific to this switch

• Tramadol lowers the seizure threshold and interacts with serotonergic drugs (SSRIs, SNRIs, MAOIs, triptans, linezolid) — screen the medication list for serotonin-syndrome risk before rotating to it.
• Ceiling dose is 400 mg/day (300 mg/day in older adults) — if the MME math calls for more, tramadol is the wrong target drug.
• Like codeine, tramadol depends on CYP2D6 for its active M1 metabolite, so analgesia varies with metabolizer status.
• Active metabolites (M3G/M6G) accumulate in renal impairment — avoid or dose-reduce morphine when eGFR is reduced, and consider an alternative agent in dialysis patients.
• Histamine release can cause pruritus and hypotension, which is not a true allergy but is often documented as one.
• Equianalgesic tables are population averages. Re-assess pain, sedation (e.g. POSS), and respiratory status within hours of the first converted dose, not days.

Frequently asked questions

How much morphine equals 200 mg of oral tramadol per day?

200 mg/day of oral tramadol is approximately 20 mg/day of oral morphine (200 mg × 0.1 MME factor ÷ 1 = 20 mg), before any cross-tolerance reduction. Most patients switching opioids should start 25–50% below the calculated equianalgesic dose.

What is the conversion factor from tramadol to morphine?

Oral tramadol has a morphine milligram equivalent (MME) factor of 0.1 and oral morphine a factor of 1, so 1 mg of tramadol ≈ 0.1 mg of morphine. Equianalgesic tables are population averages — individual response varies, so titrate to effect.

Why reduce the dose for incomplete cross-tolerance?

Tolerance to one opioid does not fully transfer to another. When rotating from tramadol to morphine, standard practice is to reduce the calculated equianalgesic dose by 25–50% and provide breakthrough doses while re-titrating. Frail or elderly patients warrant the larger reduction.

Is this conversion exact?

No. Published equianalgesic factors are averages with wide interpatient variability, and they differ slightly between references. Treat the calculated dose as a starting estimate, apply a cross-tolerance reduction, and reassess pain and sedation frequently after the switch.