Acetaminophen And Codeine and Abametapir: 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
Abametapir
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.
What's going on: Abametapir is a lotion used to treat head lice. Even though it's applied to your scalp, some of it gets into your body and can slow down a liver enzyme (called CYP3A4) that helps break down many medicines. One of those medicines is the codeine part of your acetaminophen with codeine.
Because codeine relies on your liver to be handled properly, this slowdown could change how much codeine builds up in your body and raise the chance of side effects like drowsiness, dizziness, or slowed breathing. This is based on theory, not real-world reports, so don't panic. Just let your pharmacist or doctor know you use both so they can help you time or manage them safely.
Mechanism: Abametapir is a potent CYP3A4 inhibitor; even topical application produces systemic exposure sufficient to inhibit CYP3A4-mediated metabolism of substrates, potentially increasing their exposure (AUC/Cmax).
Relevance here: Codeine undergoes partial CYP3A4 metabolism (to norcodeine), while primary analgesic activation is CYP2D6-mediated. Reduced CYP3A4 clearance may raise parent codeine exposure and opioid-related adverse effects.
- Direction: increased CYP3A4 substrate exposure
- Onset: rapid
- Evidence: theoretical
- Severity: major
Management: Avoid CYP3A4 substrates for 2 weeks after abametapir application; if unavoidable, avoid abametapir. Individualize and monitor for opioid toxicity if co-use occurs.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Avoid use of CYP3A4 substrates within 2 weeks after application of abametapir. If this is not feasible, avoid use of abametapir1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
What your care team may do:
- The documented guidance is to avoid CYP3A4 substrates for about 2 weeks after applying abametapir. If that isn't feasible, the abametapir treatment itself may be avoided instead.
- Your team may look at timing, since abametapir is a one-time lice treatment, so spacing it from your acetaminophen/codeine may be an option.
What you should do:
- Keep taking your acetaminophen with codeine as prescribed, and don't stop anything on your own.
- Tell your pharmacist or doctor before using abametapir so they can help you sequence the two safely and watch for extra drowsiness or slowed breathing.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Acetaminophen And Codeine and Abametapir together?
Abametapir can slow the breakdown of the codeine in your acetaminophen/codeine, so avoid taking it within about 2 weeks of an abametapir lice treatment unless your pharmacist or doctor okays the timing. Watch for extra drowsiness or slowed breathing if both are used. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine and Abametapir interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How is the Acetaminophen And Codeine and Abametapir interaction managed?
What your care team may do: The documented guidance is to avoid CYP3A4 substrates for about 2 weeks after applying abametapir. If that isn't feasible, the abametapir treatment itself may be avoided instead. Your team may look at timing, since abametapir is a one-time lice treatment, so spacing it from your acetaminophen/codeine may be an option. What you should do: Keep taking your acetaminophen w… 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 Abametapir 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: XEGLYZE(TM) topical lotion, abametapir topical lotion. Dr Reddy’s Laboratories Inc (per FDA), Princeton, NJ, 2020. DailyMed
Keep reading about Acetaminophen And Codeine
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