Abametapir and Lemborexant: 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
Abametapir
No brand names on recordLemborexant
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.
Abametapir is a lotion used to treat head lice. Even though you put it on your scalp, some of it can get into your body and slow down a liver enzyme (called CYP3A4) that helps break down other medicines. Lemborexant (Dayvigo) is a sleep medicine that your body clears using that same enzyme.
If the enzyme is slowed down, your body may hold on to more lemborexant than usual. That could make you extra sleepy or groggy, especially the next morning. The good news is this is easy to manage. Your care team can help you plan the timing, so be sure to tell your pharmacist or doctor that you use both.
Mechanism: Abametapir inhibits CYP3A4. Lemborexant is a CYP3A4 substrate, so co-exposure is expected to increase lemborexant AUC/Cmax.
Direction / effect: Increased lemborexant exposure, raising risk of enhanced sedation, somnolence, next-morning impairment.
- Onset: rapid
- Evidence: theoretical (mechanism-based)
- Severity: major
Management: Avoid CYP3A4 substrates, including lemborexant, within 2 weeks after topical abametapir application. If avoidance is not feasible, avoid abametapir. Coordinate timing and consider closer monitoring for excess sedation if concurrent use is unavoidable.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Within a 2-week window following abametapir application, CYP3A4 substrates should not be used. When avoiding these substrates is not possible, abametapir itself should be avoided 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
Both drugs can be used, but timing matters. Abametapir's enzyme-slowing effect can linger, so guidance is to avoid CYP3A4 medicines like lemborexant for up to 2 weeks after the abametapir lice treatment. If that is not workable, the abametapir treatment itself may be avoided.
- Keep taking your medicines as prescribed. Do not stop or change anything on your own.
- Tell your pharmacist or doctor that you use both so they can plan the timing.
- Watch for extra drowsiness or morning grogginess and report it to your care team.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Lemborexant together?
Abametapir can slow how your body clears lemborexant, so guidance is to keep them apart, avoiding lemborexant for 2 weeks after applying abametapir. Talk to your pharmacist or doctor to plan the timing. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Lemborexant 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 Abametapir and Lemborexant interaction managed?
Both drugs can be used, but timing matters. Abametapir's enzyme-slowing effect can linger, so guidance is to avoid CYP3A4 medicines like lemborexant for up to 2 weeks after the abametapir lice treatment. If that is not workable, the abametapir treatment itself may be avoided. Keep taking your medicines as prescribed. Do not stop or change anything on your own. Tell your pharmacist or doctor that y… 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 Abametapir or Lemborexant 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 Abametapir
Keep reading about Lemborexant
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