Acetaminophen and Fenoldopam: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 10, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Fenoldopam
No brand names on recordAcetaminophen
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
Increased fenoldopam concentration
Interaction Deep Dive
Concomitant oral administration of acetaminophen 1 g every eight hours and fenoldopam 100 mg has been associated with increases in peak serum fenoldopam concentrations of 30% (acutely) to 70% (chronically), increases in AUCs of fenoldopam of 50% (acutely) to 66% (chronically), and reductions in levels and AUCs of its metabolites. With acute use, no clinical adverse effects were noted1.
Why it happens (mechanism)
Competition for inorganic sulfate substrate needed for sulfation of both drugs
Common questions
Can I take Acetaminophen and Fenoldopam together?
Increased fenoldopam concentration Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen and Fenoldopam interaction?
It is rated minor. Usually limited clinical impact.
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 "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Acetaminophen or Fenoldopam 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)
- Ziemniak JA, Allison N, Boppana VK, et al: The effect of acetaminophen on the disposition of fenoldopam: competition for sulfation. Clin Pharmacol Ther 1987; 41:275-281. DOI
Keep reading about Fenoldopam
Keep reading about Acetaminophen
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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