Acetaminophen And Codeine and Telaprevir: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 1, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Acetaminophen And Codeine
Telaprevir
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. Telaprevir slows down a liver enzyme (called CYP3A4) that your body uses to process codeine. When codeine can't be broken down normally, more of it (and more of the morphine it turns into) can build up in your body. That can make the codeine's effects stronger and longer, which means more sleepiness, and in some cases dangerously slow breathing.
This concern is theoretical, meaning it's based on how these drugs work rather than lots of real-world reports, so try not to panic. Your care team can manage this safely by watching you closely and tailoring your codeine dose. Please talk with your pharmacist or doctor before changing anything.
Mechanism: Telaprevir is a potent CYP3A4 inhibitor. Codeine undergoes CYP3A4-mediated metabolism (N-demethylation to norcodeine), and CYP2D6 activation to morphine. Inhibiting CYP3A4 shifts more codeine toward the CYP2D6 pathway, increasing codeine and morphine exposure and opioid effect.
- Direction: Increased opioid effect (increased sedation, respiratory depression risk).
- Onset: Unspecified; risk greatest when inhibitor is added to a stable codeine dose.
- Evidence: Theoretical.
- Management: Monitor for respiratory depression and sedation; consider codeine dose reduction until stable effects observed. On telaprevir discontinuation, monitor for withdrawal and consider dose increase.
What happens
Increased codeine and morphine exposure
Interaction Deep Dive
Taking codeine together with CYP3A4 inhibitors has led to elevated levels of both codeine and morphine, an effect that may intensify or extend adverse reactions and could produce respiratory depression that is potentially fatal, especially in cases where the inhibitor is introduced after a patient has already reached a stable codeine dose. When the two agents must be used together, patients should be watched carefully for signs of sedation and respiratory depression, and reducing the codeine dose should be considered until the drug effects become stable. Conversely, when a CYP3A4 inhibitor is being stopped, patients should be observed for indications of opioid withdrawal, with consideration given to raising the codeine dose until stable drug effects are seen12.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated codeine metabolism
How to manage this interaction
The good news: this is manageable when your team knows you take both.
- Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise.
- Your care team may monitor you more closely for excess sleepiness or slowed, shallow breathing, especially soon after telaprevir is started.
- Your codeine dose may need to be adjusted and individualized by your team until your response is stable.
- If telaprevir is ever stopped, tell your team, since your codeine dose may need to be revisited to avoid withdrawal.
Seek help right away for very slow breathing, extreme drowsiness, or trouble waking. Raise any concerns with your pharmacist or prescriber.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Acetaminophen And Codeine and Telaprevir together?
Telaprevir can raise codeine and morphine levels and increase the risk of heavy sedation or slowed breathing, so use both only under close monitoring and let your care team adjust your codeine dose as needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine and Telaprevir 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 Telaprevir interaction managed?
The good news: this is manageable when your team knows you take both. Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. Your care team may monitor you more closely for excess sleepiness or slowed, shallow breathing, especially soon after telaprevir is started. Your codeine dose may need to be adjusted and individualized by your team until your response 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 Acetaminophen And Codeine or Telaprevir 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 (2)
- 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
Keep reading about Acetaminophen And Codeine
Keep reading about Telaprevir
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