How many mg of morphine equals a 25 mcg/h fentanyl patch?

A 25 mcg/h fentanyl patch corresponds to roughly 60–90 mg oral morphine equivalents per day, which is about 60–90 mg/day of oral morphine. Fentanyl conversions use ranges, not a single factor, because absorption varies between patients.

Who should NOT be started on a fentanyl patch?

Opioid-naïve patients. Transdermal fentanyl is only appropriate for patients already tolerant to at least ~60 mg oral morphine equivalents per day for a week or more. Starting a patch in a naïve patient can cause fatal respiratory depression.

When does a new fentanyl patch start working?

Serum levels rise slowly over 12–24 hours after the first patch is applied. Continue short-acting opioid coverage during that window, and do not titrate the patch more often than every 3 days.

Morphine to Fentanyl (transdermal patch): how to convert safely

Name: Morphine to Fentanyl (transdermal patch) Conversion | scopemd
Creator: Yasmine Abbey, MD, MSc

Bottom line

Each 25 mcg/h of transdermal fentanyl ≈ 60–90 mg oral morphine equivalents/day. Fentanyl conversions use ranges, not a single factor — and patches are only for opioid-tolerant patients (≥60 OME/day for ≥1 week).

Patch sizes vs. morphine equivalents

Patch (mcg/h)	≈ OME (mg/day)	≈ oral morphine (mg/day)
12	29–43	29–43
25	60–90	60–90
37	89–133	89–133
50	120–180	120–180
62	149–223	149–223
75	180–270	180–270
100	240–360	240–360

Ranges reflect the commonly used 25 mcg/h ≈ 60–90 OME/day equivalence; verify against your institutional table.

Method: rotating onto the patch

Confirm opioid tolerance (≥60 OME/day for ≥1 week) — patches are never for naïve patients.
Total the 24-hour morphine dose and convert to OME (factor 1).
Select the patch using the conservative end of the range and round DOWN to an available size.
Continue short-acting coverage for the first 12–24 h while levels rise; do not re-titrate the patch sooner than 3 days.

Cautions

Fentanyl patches are only for opioid-tolerant patients (≥60 OME/day for ≥1 week). Applying a patch to an opioid-naïve patient can be fatal.
Absorption takes 12–24 h to reach steady state and continues 12–24 h after removal — overlap short-acting coverage on the way up, and do not stack doses on the way down.
Fever, external heat sources, and broken skin all increase absorption unpredictably.
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.

Build the full regimen

The opioid regimen builder handles fentanyl patch selection from a mixed home regimen, including rounding to available patch sizes and frail-patient reductions.

Frequently asked questions

How many mg of morphine equals a 25 mcg/h fentanyl patch?: A 25 mcg/h fentanyl patch corresponds to roughly 60–90 mg oral morphine equivalents per day, which is about 60–90 mg/day of oral morphine. Fentanyl conversions use ranges, not a single factor, because absorption varies between patients.
Who should NOT be started on a fentanyl patch?: Opioid-naïve patients. Transdermal fentanyl is only appropriate for patients already tolerant to at least ~60 mg oral morphine equivalents per day for a week or more. Starting a patch in a naïve patient can cause fatal respiratory depression.
When does a new fentanyl patch start working?: Serum levels rise slowly over 12–24 hours after the first patch is applied. Continue short-acting opioid coverage during that window, and do not titrate the patch more often than every 3 days.

Creado y mantenido por Yasmine Abbey, MD, MSc · Última revisión: 2026-08-05

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