Abametapir and Simeprevir: 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 recordSimeprevir
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 only put it on your scalp, a little gets into your body and can briefly slow down a liver enzyme called CYP3A4. That enzyme is one of the main ways your body clears simeprevir (Olysio), a medicine for hepatitis C. With the enzyme slowed, more simeprevir can build up in your blood, which may raise the chance of side effects.
This is based on how the drugs work rather than on real-world reports, so it is a caution, not a sure thing. The good news is your care team can plan the timing so both work safely. Please check with your pharmacist or doctor before using both.
Mechanism: Abametapir inhibits CYP3A4. Simeprevir is a CYP3A4 substrate, so its metabolism is reduced, increasing simeprevir exposure (AUC/Cmax) and the risk of concentration-related adverse effects.
- Direction: Increased simeprevir effect (neither drug is a prodrug here).
- Onset: Rapid.
- Evidence: Theoretical, based on abametapir's known CYP3A4 inhibition.
- Severity: Major.
Management: Avoid CYP3A4 substrates, including simeprevir, for 2 weeks after abametapir application. If concurrent use is unavoidable, avoid abametapir. If co-exposure occurs, monitor more closely for simeprevir-related toxicity.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
For a period of 2 weeks following the application of abametapir, refrain from using CYP3A4 substrates. Should that not be possible, do not use abametapir1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
Both of these can usually be handled with good timing and communication with your care team.
- Keep taking your medicines as prescribed and do not stop anything on your own.
- Because abametapir can affect the enzyme that clears simeprevir for a while, the recommendation is to avoid CYP3A4 medicines like simeprevir for about 2 weeks after using abametapir. If that is not possible, your team may avoid the abametapir instead.
- Tell your pharmacist and prescriber that you use both, and ask about the best timing.
- Report any new or stronger side effects while on simeprevir so your team can monitor you more closely.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Simeprevir together?
Abametapir can slow the breakdown of simeprevir and raise its levels, so the usual advice is to avoid simeprevir for about two weeks after using abametapir; ask your pharmacist or doctor to help time them safely. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Simeprevir 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 Simeprevir interaction managed?
Both of these can usually be handled with good timing and communication with your care team. Keep taking your medicines as prescribed and do not stop anything on your own. Because abametapir can affect the enzyme that clears simeprevir for a while, the recommendation is to avoid CYP3A4 medicines like simeprevir for about 2 weeks after using abametapir. If that is not possible, your team may avoid… 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 Simeprevir 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 Simeprevir
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist