Cinacalcet 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
Cinacalcet
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 if you take codeine (the pain reliever combined with acetaminophen in products like Tylenol with Codeine) along with cinacalcet. Codeine is a prodrug, which means your body has to convert it into morphine to get the real pain relief. It uses an enzyme called CYP2D6 to do that.
Cinacalcet slows that enzyme down, so your body may make less morphine. The result? Your pain medicine may not work as well, and if you regularly use codeine, you could feel mild withdrawal. This is a theoretical concern, not something proven in studies, and your care team can manage it easily by watching how well your pain is controlled and adjusting your dose if needed.
Mechanism: Cinacalcet is a CYP2D6 inhibitor. Codeine is a prodrug requiring CYP2D6-mediated O-demethylation to morphine, its active metabolite.
- Direction: Inhibition raises parent codeine exposure but reduces morphine formation, lowering analgesic efficacy and risking opioid withdrawal in chronic users.
- Evidence: Theoretical; magnitude and onset not characterized.
- Management: If co-administered, monitor for reduced analgesia and withdrawal; the codeine dose may need to be individualized upward by the care team. On discontinuing cinacalcet, anticipate restored morphine formation and monitor for sedation and respiratory depression, with downward dose adjustment as needed.
What happens
Increased codeine exposure and reduced active metabolite (morphine) exposure
Interaction Deep Dive
Concomitant use of codeine and a CYP2D6 inhibitor may reduce plasma concentrations of morphine, the active metabolite of codeine, thus potentially leading to reduced efficacy and withdrawal symptoms. If concomitant use is necessary, monitor patients for withdrawal symptoms and consider increasing the codeine dose. Once the CYP2D6 inhibitor is discontinued, consider reducing the codeine dose and monitor for signs and symptoms of respiratory depression and sedation312.
Why it happens (mechanism)
Inhibition of CYP2D6-mediated codeine metabolism
How to manage this interaction
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. This is a manageable situation your care team can tailor for you.
- Your team may watch how well your pain is being controlled and check for any withdrawal-type symptoms if you use codeine regularly.
- Your codeine dose may be adjusted and individualized by your care team while you are on cinacalcet.
- If cinacalcet is ever stopped, tell your prescriber, since the codeine dose may need to be lowered and you may be watched for extra drowsiness or slowed breathing.
Raise any change in pain relief with your pharmacist or doctor.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Cinacalcet and Acetaminophen And Codeine together?
Cinacalcet can reduce how well codeine controls pain by blocking its conversion to morphine, so your care team may adjust your codeine dose and monitor your pain relief. Keep taking both as prescribed and report any drop in pain control or withdrawal symptoms. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Cinacalcet 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 Cinacalcet and Acetaminophen And Codeine interaction managed?
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. This is a manageable situation your care team can tailor for you. Your team may watch how well your pain is being controlled and check for any withdrawal-type symptoms if you use codeine regularly. Your codeine dose may be adjusted and individualized by your care team while you are on cinacalcet. If cinacalcet is… 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 Cinacalcet 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 (3)
- Product Information: Codeine sulfate oral solution, codeine sulfate oral solution. Hikma Pharmaceuticals USA Inc(per FDA), Berkeley Heights, NJ, 2023. DailyMed
- Product Information: Codeine sulfate oral tablets, codeine sulfate oral tablets. Hikma Pharmaceuticals USA Inc. (per FDA), Berkeley Heights, NJ, 2023. DailyMed
- Product Information: codeine sulfate oral tablets, codeine sulfate oral tablets. West-Ward Pharmaceuticals Corp. (per FDA), Eatontown, NJ, 2017. DailyMed
Keep reading about Acetaminophen And Codeine
Keep reading about Cinacalcet
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