Acetaminophen And Codeine and Rifapentine: 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
Rifapentine
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.
Rifapentine (Priftin) can make your codeine work less well. Codeine is a pain reliever that your body has to turn into its active form to do its job. Rifapentine speeds up the liver enzymes that break codeine down, so less of it becomes active pain relief. This means the codeine part of your acetaminophen and codeine may not control pain as well, and if your body has gotten used to the opioid, you could feel withdrawal symptoms like aches, chills, sweating, or an upset stomach.
The good news is this is very manageable. Do not stop or change either medicine on your own. Your care team can watch how you are doing and adjust your dose if needed.
Effect: Rifapentine, a CYP3A4 inducer, increases codeine metabolism, shifting it toward norcodeine and reducing the fraction available for CYP2D6 activation to morphine. Net result is reduced opioid exposure, decreased analgesic efficacy, and possible withdrawal in physically dependent patients.
- Mechanism: CYP3A4 induction of codeine metabolism (codeine is a prodrug requiring CYP2D6 activation to morphine).
- Direction: Reduced opioid effect.
- Evidence: Theoretical; severity rated major.
- Management: Monitor for reduced analgesia and withdrawal; consider increasing codeine dose if needed. If rifapentine is discontinued, anticipate rising opioid levels, reduce codeine dose, and monitor for sedation or respiratory depression.
What happens
Reduced codeine and morphine exposure, reduced opioid efficacy and precipitation of opioid withdrawal
Interaction Deep Dive
When codeine is taken alongside CYP3A4 inducers, codeine concentrations may fall while norcodeine concentrations rise, and metabolism through CYP2D6 may be diminished, producing lower morphine levels. This can lead to reduced effectiveness or trigger a withdrawal syndrome in patients who have become physically dependent. Should the combination be required, monitor patients carefully for loss of efficacy or indications of opioid withdrawal syndrome, and raise the codeine dose if needed. When a CYP3A4 inducer is being stopped, consider lowering the codeine dose and watch patients closely for evidence of respiratory depression or sedation12.
Why it happens (mechanism)
Induction of CYP3A4-mediated codeine metabolism
How to manage this interaction
Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. This interaction can usually be managed with monitoring and dose tailoring.
- Your care team may watch closely for pain that is not well controlled or for withdrawal signs such as body aches, chills, sweating, restlessness, or stomach upset.
- Your codeine dose may need to be adjusted and individualized by your care team if it stops working well.
- If rifapentine is ever stopped, tell your team, since your codeine dose may then need to be lowered to avoid too much sedation.
- Report new or worsening pain or any withdrawal symptoms to your pharmacist or doctor.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Acetaminophen And Codeine and Rifapentine together?
Rifapentine can speed up how your body clears codeine, making the codeine in your acetaminophen and codeine less effective and possibly triggering withdrawal. Do not change anything on your own; your care team can monitor you and adjust the dose as needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine and Rifapentine 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 Rifapentine interaction managed?
Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. This interaction can usually be managed with monitoring and dose tailoring. Your care team may watch closely for pain that is not well controlled or for withdrawal signs such as body aches, chills, sweating, restlessness, or stomach upset. Your codeine dose may need to be adjusted and individualized by you… 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 Rifapentine 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 Rifapentine
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.
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