Furosemide and Acetaminophen And Codeine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jun 30, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Acetaminophen And Codeine
Furosemide
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.
You're taking a water pill (furosemide, brand name Lasix) along with a pain medicine that contains codeine. Furosemide helps your body get rid of extra fluid and can help control blood pressure. The concern here is that opioids like codeine can trigger your body to hold onto more water (by releasing a hormone that keeps fluid in), which could make the water pill work a little less well.
To be clear, this is a theoretical concern, not something proven in strong studies. If you notice you're making less urine, feel more swollen, or your blood pressure creeps up, mention it. Your care team can easily manage this by watching you and adjusting your dose if needed.
Effect: Potential reduced diuretic efficacy of furosemide when combined with codeine.
Mechanism: Opioid-mediated increase in antidiuretic hormone (ADH) release promotes water retention, opposing the natriuretic/diuretic and antihypertensive action of furosemide. This is a PD (pharmacodynamic) interaction, not CYP-mediated; codeine's prodrug status (CYP2D6 activation to morphine) is not relevant to this mechanism.
- Direction: Reduced furosemide effect.
- Onset: Unspecified.
- Evidence: Theoretical; magnitude undefined.
- Management: Monitor urine output, fluid status/edema, and blood pressure. Furosemide dose may be adjusted and individualized as needed.
What happens
Reduced diuretic efficacy
Interaction Deep Dive
Concomitant use of codeine with diuretics may reduce the efficacy of diuretics by inducing the release of anti-diuretic hormone. Monitor patients for signs of diminished diuresis and/or effects on blood pressure and increase the dosage of the diuretic as needed1.
Why it happens (mechanism)
Increased opioid-mediated release of antidiuretic hormone
How to manage this interaction
Keep taking both medications as prescribed unless your prescriber tells you otherwise. This interaction is theoretical, and your care team can manage it easily.
- Watch for signs the water pill may be working less well: making less urine, more swelling in your legs or ankles, sudden weight gain, or higher blood pressure readings.
- Your team may monitor you more closely, and your furosemide dose may need to be adjusted and individualized if signs of reduced diuresis appear.
- Bring any of these changes to your pharmacist or doctor so they can tailor your treatment.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Furosemide and Acetaminophen And Codeine together?
Codeine may slightly reduce how well furosemide removes fluid, but this is only a theoretical concern. Keep taking both as prescribed and tell your care team if you notice less urine output, more swelling, or higher blood pressure. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Furosemide and Acetaminophen And Codeine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Furosemide and Acetaminophen And Codeine interaction managed?
Keep taking both medications as prescribed unless your prescriber tells you otherwise. This interaction is theoretical, and your care team can manage it easily. Watch for signs the water pill may be working less well: making less urine, more swelling in your legs or ankles, sudden weight gain, or higher blood pressure readings. Your team may monitor you more closely, and your furosemide dose may n… Management is individual — always follow your own care team's guidance.
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 Furosemide or Acetaminophen And Codeine 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 a safer alternative to one of these medications for me?
References (1)
- Product Information: CARISOPRODOL, ASPIRIN, CODEINE PHOSPHATE oral tablets, carisoprodol, aspirin, codeine phosphate oral tablets. Ingenus Pharmaceuticals LLC (per DailyMed), Orlando, FL, 2021. DailyMed
Keep reading about Acetaminophen And Codeine
Keep reading about Furosemide
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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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