Chloroprocaine and Morphine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Morphine
No brand names on recordChloroprocaine
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Antagonism of the analgesic effect of epidural morphine by epidural chloroprocaine
Interaction Deep Dive
Epidural chloroprocaine, administered during cesarean section (CS), was found to antagonize the analgesic effect of epidural morphine used for postpartum pain in a randomized, double-blind study1.
Why it happens (mechanism)
Unknown
Literature reports
1 report — tap to read
a) Epidural chloroprocaine, administered during cesarean section (CS), was found to antagonize the analgesic effect of epidural morphine used for postpartum pain in a randomized double blind study. Patients were randomized to receive either chloroprocaine (12 patients), chloroprocaine with epinephrine (16 patients), or lidocaine with epinephrine (14 patients). The doses were adjusted to obtain anesthesia to the level of T6-T4. All patients received 5 mg of epidural morphine after delivery and were started on epidural morphine by patient controlled analgesia with 1 mg dose increments with a 6 minute lockout and a 4-hour maximum of 30 mg. The average amount of morphine used in 24 hours was significantly higher in the chloroprocaine and the chloroprocaine with epinephrine groups compared to the lidocaine group, 30.2, 27.72, and 4.07 mg morphine, respectively. Most of the difference in morphine usage occurred in the 2 to 16 hours after CS; by 24 hours after CS the usage of morphine was essentially the same for all groups. The mechanism by which chloroprocaine antagonizes the action of epidural morphine is not known 1.
Common questions
Can I take Chloroprocaine and Morphine together?
Antagonism of the analgesic effect of epidural morphine by epidural chloroprocaine Always confirm with your pharmacist or prescriber before making any change.
How serious is the Chloroprocaine and Morphine interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "established". Well documented — supported by controlled studies or strong clinical data.
Questions for your pharmacist
- Does my dose of Chloroprocaine or Morphine need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (1)
- Karambelkar DJ & Ramanathan S: 2-chloroprocaine antagonism of epidural morphine analgesia. Acta Anaesthesiol Scand 1997; 41:774-778. PubMed
Keep reading about Morphine
Keep reading about Chloroprocaine
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