Acetaminophen And Codeine and Trichlormethiazide: 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
Trichlormethiazide
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.
Here's what's going on. Your pain medicine contains codeine, an opioid. Codeine can cause your body to release a hormone that tells your kidneys to hold onto water. Your trichlormethiazide is a water pill (diuretic) meant to help you get rid of extra fluid and control your blood pressure. So the codeine may work against the water pill and make it a little less effective.
The good news is that this concern is mostly theoretical, and your care team can easily stay on top of it. Keep taking both as prescribed, and your doctor can watch your blood pressure and fluid and adjust your water pill dose if needed.
Effect: Possible reduced diuretic efficacy of trichlormethiazide when combined with codeine (in the acetaminophen/codeine product).
Mechanism: Opioid-mediated increase in antidiuretic hormone (ADH) release, promoting water retention and pharmacodynamically opposing the thiazide. This is a PD interaction, not a CYP-based PK effect. Codeine is a prodrug activated via CYP2D6, but that pathway is not what drives this interaction.
Evidence: Theoretical; onset unspecified; severity rated major.
Management:
- Monitor diuresis, volume status, and blood pressure.
- Titrate/increase the diuretic dose as clinically indicated.
- Individualize based on response.
What happens
Reduced diuretic efficacy
Interaction Deep Dive
Taking codeine together with diuretics can diminish diuretic effectiveness because it prompts the secretion of anti-diuretic hormone. Watch patients for indications of reduced urine output and/or changes in blood pressure, and raise the diuretic dose when required1.
Why it happens (mechanism)
Increased opioid-mediated release of antidiuretic hormone
How to manage this interaction
The practical picture: This is a theoretical concern, and it is very manageable. Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise.
- Your care team may watch your blood pressure and check for signs your water pill is working less well, like swelling in your legs or feet, sudden weight gain, or less urination.
- If needed, your trichlormethiazide dose may be adjusted and individualized by your care team.
What to do: Tell your pharmacist or doctor you take both. Report new swelling, weight gain, or blood pressure changes so they can fine-tune your dose.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Acetaminophen And Codeine and Trichlormethiazide together?
Codeine may slightly blunt how well your trichlormethiazide water pill works by causing fluid retention, but this is theoretical and easily managed with blood pressure checks and dose adjustment if needed. Keep taking both as prescribed and let your care team know you use both. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine and Trichlormethiazide 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 Acetaminophen And Codeine and Trichlormethiazide interaction managed?
The practical picture: This is a theoretical concern, and it is very manageable. Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. Your care team may watch your blood pressure and check for signs your water pill is working less well, like swelling in your legs or feet, sudden weight gain, or less urination. If needed, your trichlormethiazide dose may be a… 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.
Questions for your pharmacist
- Does my dose of Acetaminophen And Codeine or Trichlormethiazide 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 Trichlormethiazide
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist