Acetaminophen Rectal and Acenocoumarol: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 10, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Acenocoumarol
No brand names on recordAcetaminophen Rectal
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
Potentiation of anticoagulant effect
Interaction Deep Dive
The anticoagulant effect of acenocoumarol may be potentiated by acetaminophen administration. A 72-year-old male stabilized on acenocoumarol 2 mg daily began self-medicating with acetaminophen 1 to 2 grams daily for lower back pain. The consistency of acetaminophen dosing is not known, but his International Normalized Ratio (INR) values remained stable with an average INR of 2.46. Approximately two weeks after discontinuing acetaminophen, his INR decreased to 1.62. One week later the INR was 1.67. The patient restarted acetaminophen 1 g daily and his INR increased to 2.02 within a week1.
Why it happens (mechanism)
Inhibition of acenocoumarol metabolism or interference with clotting factor formation
Common questions
Can I take Acetaminophen Rectal and Acenocoumarol together?
Potentiation of anticoagulant effect Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen Rectal and Acenocoumarol interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Acetaminophen Rectal or Acenocoumarol 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)
- Bagheri H, Bernhard NB, & Montastruc JL: Potentiation of the acenocoumarol anticoagulant effect by acetaminophen (letter). Ann Pharmacother 1999; 33:506. PubMed
Keep reading about Acenocoumarol
Keep reading about Acetaminophen Rectal
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