Acetaminophen And Codeine and Hydrochlorothiazide: 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
Hydrochlorothiazide
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.
Your pain medicine contains codeine, an opioid. Codeine can nudge your body to hold onto more water by raising a hormone called antidiuretic hormone (ADH). Your hydrochlorothiazide is a water pill that helps you get rid of extra fluid and lowers blood pressure. When taken together, the codeine may work against the water pill, so it might not remove fluid or control your blood pressure quite as well.
This is based on theory, not strong proof, so please don't worry. If your blood pressure creeps up or your swelling seems worse, your care team can simply adjust your water pill dose. Keep taking both as prescribed and check in with your pharmacist or doctor.
Effect: Codeine (in the acetaminophen/codeine combination) may reduce the efficacy of hydrochlorothiazide.
Mechanism: Opioid-mediated increase in antidiuretic hormone (ADH) release promotes water retention, opposing the natriuretic/antihypertensive effect of the thiazide.
- Direction: Reduced diuretic effect (PD antagonism), not a CYP-based PK interaction.
- Onset: Unspecified.
- Evidence: Theoretical; magnitude not quantified.
- Management: Monitor diuresis, edema, weight, and blood pressure. The HCTZ dose may need to be individualized/increased by the care team if diminished response 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
Both medicines can be used together with some awareness.
- Keep taking both as prescribed unless your prescriber tells you otherwise.
- Your care team may monitor you more closely for signs the water pill is working less well, such as more swelling, weight gain, or higher blood pressure readings.
- If reduced effect is seen, your hydrochlorothiazide dose may be adjusted and individualized by your team.
Tell your pharmacist or doctor if you notice new or worsening swelling in your legs, sudden weight gain, or blood pressure that runs higher than usual.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Acetaminophen And Codeine and Hydrochlorothiazide together?
The codeine in your pain medicine may make hydrochlorothiazide work a little less well by causing fluid retention; watch for swelling or higher blood pressure and let your care team adjust the dose if needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine and Hydrochlorothiazide 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 Hydrochlorothiazide interaction managed?
Both medicines can be used together with some awareness. Keep taking both as prescribed unless your prescriber tells you otherwise. Your care team may monitor you more closely for signs the water pill is working less well, such as more swelling, weight gain, or higher blood pressure readings. If reduced effect is seen, your hydrochlorothiazide dose may be adjusted and individualized by your team.… 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 Acetaminophen And Codeine or Hydrochlorothiazide 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 Hydrochlorothiazide
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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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