Delavirdine 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
Delavirdine
Acetaminophen And Codeine
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 delavirdine (Rescriptor) is a strong blocker of a liver enzyme called CYP3A4. When you also take codeine, that blocking can cause more codeine and its active form (morphine) to build up in your body. In plain terms, the pain medicine's effects (drowsiness, and slower or shallow breathing) could become stronger or last longer.
This warning is based mostly on theory rather than lots of real-world cases, so please don't worry or change anything on your own. The important thing is to watch for unusual sleepiness or trouble breathing, and talk with your pharmacist or doctor. They can adjust your dose and keep a closer eye on you so both medicines work safely together.
Effect: Increased codeine and its active metabolite morphine exposure via CYP3A4 inhibition by delavirdine, a potent CYP3A4 inhibitor. Reduced CYP3A4-mediated clearance shifts codeine toward the CYP2D6 (morphine) pathway, raising active opioid levels.
- Direction: Increased opioid effect (sedation, respiratory depression).
- Onset: Unspecified; risk notable when inhibitor added to stable codeine dose.
- Evidence: Theoretical.
- Management: Monitor for respiratory depression and sedation; consider codeine dose reduction until stable effects observed. If delavirdine is discontinued, monitor for opioid withdrawal and consider increasing codeine dose.
What happens
Increased codeine and morphine exposure
Interaction Deep Dive
Concomitant use of codeine with CYP3A4 inhibitors has resulted in increased codeine and morphine concentrations, which could increase or prolong adverse reactions and may cause potentially fatal respiratory depression, particularly when an inhibitor is added after a stable dose of codeine is achieved. If concomitant use is needed, closely monitor patients for respiratory depression and sedation, and consider dose reduction of codeine until stable drug effects have been observed. If a CYP3A4 inhibitor is being discontinued, monitor patients for signs of opioid withdrawal, and consider increasing dose of codeine until stable drug effects have been observed12.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated codeine metabolism
How to manage this interaction
Keep taking both medicines exactly as prescribed unless your care team tells you otherwise. Because delavirdine can raise codeine and morphine levels, your team may take steps to keep you safe:
- Watch closely for excessive sleepiness, confusion, or slow/shallow breathing, especially soon after starting delavirdine on a steady codeine dose.
- Your codeine dose may need to be adjusted and individualized by your care team, and they may monitor you more closely.
- If delavirdine is later stopped, tell your team, since your codeine dose may need to be revisited to avoid withdrawal or reduced pain control.
Contact your pharmacist or prescriber promptly if you notice breathing problems or heavy drowsiness.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Delavirdine and Acetaminophen And Codeine together?
Delavirdine can increase codeine and morphine levels, raising the risk of heavy sedation and dangerous slowed breathing. Keep taking both as prescribed, watch for excessive drowsiness or breathing trouble, and let your care team adjust your dose and monitor you. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Delavirdine 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 Delavirdine and Acetaminophen And Codeine interaction managed?
Keep taking both medicines exactly as prescribed unless your care team tells you otherwise. Because delavirdine can raise codeine and morphine levels, your team may take steps to keep you safe: Watch closely for excessive sleepiness, confusion, or slow/shallow breathing, especially soon after starting delavirdine on a steady codeine dose. Your codeine dose may need to be adjusted and individualize… 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 Delavirdine 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 (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
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