Chlorthalidone 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
Chlorthalidone
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 chlorthalidone, a water pill that helps your body get rid of extra fluid and control blood pressure. The codeine in your acetaminophen-codeine tablets can cause your body to hold on to more water by nudging up a hormone that keeps fluid in. In theory, that could make your water pill work a little less well, so you might notice less urine or blood pressure that creeps up.
Please don't stop either medicine. This is based on theory, not strong proof, and it's very manageable. Your care team can simply keep an eye on your blood pressure and swelling, and adjust your water pill dose if needed. Bring it up at your next visit.
Effect: Codeine may reduce the diuretic and antihypertensive efficacy of chlorthalidone.
Mechanism: Opioid-mediated increase in antidiuretic hormone (ADH) release promotes water retention, antagonizing thiazide-like diuresis. This is a PD interaction; codeine's CYP2D6 activation to morphine is not the relevant pathway here.
- Direction: reduced diuretic effect
- Onset: unspecified
- Evidence: theoretical; magnitude undefined
- Severity on file: major
Management: Monitor urine output, edema, weight, and blood pressure. The chlorthalidone dose may be adjusted and individualized upward if diminished diuresis is observed.
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 medicines as prescribed unless your prescriber tells you otherwise. This concern is theoretical, and your care team can manage it easily.
- Your team may monitor you more closely, watching your blood pressure, any swelling in your legs or feet, your weight, and how much you're urinating.
- If your water pill seems less effective, your chlorthalidone dose may be adjusted and individualized by your care team.
- Tell your pharmacist or doctor if you notice increased swelling, sudden weight gain, or rising blood pressure.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Chlorthalidone and Acetaminophen And Codeine together?
Codeine may slightly weaken how well your chlorthalidone water pill works by causing fluid retention, but this is theoretical and easily managed. Keep taking both as prescribed and let your care team watch your blood pressure, swelling, and weight. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Chlorthalidone 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 Chlorthalidone and Acetaminophen And Codeine interaction managed?
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. This concern is theoretical, and your care team can manage it easily. Your team may monitor you more closely, watching your blood pressure, any swelling in your legs or feet, your weight, and how much you're urinating. If your water pill seems less effective, your chlorthalidone dose may be adjusted and individual… 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 Chlorthalidone 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 Chlorthalidone
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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:
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