Abametapir and Voxilaprevir: 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 recordVoxilaprevir
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. Abametapir is a lotion used to treat head lice. Even though it goes on your scalp, some of it gets into your body and can briefly block a liver enzyme called CYP3A4. Voxilaprevir, part of your hepatitis C treatment, is cleared by that same enzyme.
So if you use them close together, your body may not break down the voxilaprevir as well, and the amount in your blood could rise. That could mean more side effects. This is a theoretical concern based on how the drugs work, not on reports of people being harmed, but because it's rated serious, it's worth a quick call to your pharmacist or doctor. They can easily manage the timing for you.
Mechanism: Abametapir inhibits CYP3A4. Voxilaprevir is a CYP3A4 substrate, so co-exposure is predicted to reduce its metabolism and increase systemic exposure (AUC/Cmax), potentially raising the risk of dose-related adverse effects. Onset is rapid; enzyme inhibition can persist after a single topical application.
- Direction: increased voxilaprevir exposure (inhibition, not induction; neither agent is affected by prodrug considerations here)
- Evidence: theoretical; no clinical magnitude quantified
- Management: Per labeling, avoid CYP3A4 substrates for 2 weeks after abametapir application. If concurrent therapy is unavoidable, avoid abametapir. Confirm timing with the care team.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Do not administer CYP3A4 substrates during the 2-week period following abametapir application. Should this be unavoidable, refrain from using abametapir1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
The good news: this is manageable mostly through timing.
- Keep taking your hepatitis C medication (voxilaprevir) as prescribed. Do not stop it on your own.
- The documented guidance is to avoid CYP3A4 substrates, including voxilaprevir, for 2 weeks after applying abametapir lice lotion. If that isn't practical, the alternative is to avoid the abametapir instead.
- Before using any lice treatment, tell your pharmacist or prescriber that you are on voxilaprevir so they can choose the safest option and set the right timing.
Your care team can coordinate this so both conditions are treated safely.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Voxilaprevir together?
Abametapir can raise voxilaprevir levels by blocking the enzyme that clears it, so avoid voxilaprevir for 2 weeks after using abametapir (or skip the abametapir). Check with your pharmacist before using any lice treatment. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Voxilaprevir 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 Voxilaprevir interaction managed?
The good news: this is manageable mostly through timing. Keep taking your hepatitis C medication (voxilaprevir) as prescribed. Do not stop it on your own. The documented guidance is to avoid CYP3A4 substrates, including voxilaprevir, for 2 weeks after applying abametapir lice lotion. If that isn't practical, the alternative is to avoid the abametapir instead. Before using any lice treatment, tell… 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 Voxilaprevir 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 Voxilaprevir
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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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