Velpatasvir 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
Abametapir
No brand names on recordVelpatasvir
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.
Abametapir is a lotion used to treat head lice. Even though you put it on your scalp, a little gets into your body and can briefly slow down a liver enzyme called CYP3A4. That enzyme helps clear velpatasvir (part of a hepatitis C treatment) from your body.
When that enzyme is slowed, velpatasvir can build up higher than expected, which could raise the chance of side effects. This is based mostly on how the drugs work in theory rather than reports in real patients, but it's still worth taking seriously. The good news is your care team can plan the timing so both treatments work safely. Always tell your pharmacist and doctor about every medicine you use.
Mechanism: Abametapir inhibits CYP3A4. Velpatasvir is a CYP3A4 substrate, so co-exposure is predicted to reduce its clearance and increase AUC/Cmax.
- Direction: Increased velpatasvir exposure (neither agent relevant as a prodrug here).
- Onset: Rapid; enzyme inhibition can persist, hence the 2-week window after topical application.
- Evidence: Theoretical.
- Severity: Major.
- Management: Avoid CYP3A4 substrates, including velpatasvir, within 2 weeks after abametapir application. If concurrent use is unavoidable, avoid abametapir. Coordinate timing with the care team.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Within a 2 week window following abametapir application, refrain from administering CYP3A4 substrates. Should that not be possible, abametapir should not be used 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
Both drugs are usually easy to manage with a little planning around timing.
- Keep taking your prescribed medicines and do not stop either on your own.
- Tell your pharmacist and prescriber that you use velpatasvir before any lice treatment is applied.
- The recommended approach is to avoid using CYP3A4 substrates like velpatasvir within 2 weeks after applying abametapir. If that spacing isn't possible, the care team may choose to avoid the abametapir treatment instead.
- Your team can pick the best timing or an alternative lice treatment for you.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Velpatasvir and Abametapir together?
Abametapir can raise velpatasvir levels by briefly blocking the CYP3A4 enzyme, so avoid velpatasvir (and other CYP3A4 medicines) for 2 weeks after applying abametapir, or skip the abametapir if that isn't possible. Check timing with your pharmacist or doctor. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Velpatasvir 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 Velpatasvir and Abametapir interaction managed?
Both drugs are usually easy to manage with a little planning around timing. Keep taking your prescribed medicines and do not stop either on your own. Tell your pharmacist and prescriber that you use velpatasvir before any lice treatment is applied. The recommended approach is to avoid using CYP3A4 substrates like velpatasvir within 2 weeks after applying abametapir. If that spacing isn't possible,… 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 Velpatasvir 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 Abametapir
Keep reading about Velpatasvir
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major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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