Abametapir and Tezacaftor: 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 recordTezacaftor
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. After you use it, it can slow down a liver enzyme called CYP3A4 for a couple of weeks. Tezacaftor (part of your cystic fibrosis medicine) is broken down by that same enzyme.
When the enzyme is slowed, tezacaftor can build up higher than usual in your body, which could mean more side effects. This is based on how the drugs work rather than on real-world reports, but it's still worth taking seriously. The good news is your care team can plan around it, often by spacing out the timing. Please check with your pharmacist or doctor before using both.
Mechanism: Abametapir is a potent CYP3A4 inhibitor. Tezacaftor is a CYP3A4 substrate, so co-exposure is expected to reduce its clearance and increase AUC/Cmax.
- Direction: increased tezacaftor exposure, potentially greater adverse effects.
- Onset: rapid; inhibition can persist for approximately 2 weeks after a single topical application.
- Evidence: theoretical (based on enzyme inhibition, not clinical reports).
- Management: Avoid CYP3A4 substrates such as tezacaftor within 2 weeks after applying abametapir. If concurrent use cannot be avoided, avoid abametapir. Dose adjustment may be individualized and monitoring increased by the care team.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
For a period of 2 weeks following abametapir application, refrain from using CYP3A4 substrates. Should that not be possible, abametapir itself should not be used 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
What your care team may do:
- Try to separate the two, since abametapir's enzyme-blocking effect can last about 2 weeks after you apply it.
- Consider a different lice treatment if you need to stay on tezacaftor.
- Monitor you more closely if both are truly needed, and individualize your plan.
What you should do:
- Keep taking your tezacaftor as prescribed. Do not stop anything on your own.
- Before using abametapir lotion, tell your pharmacist or doctor you take tezacaftor so they can help you time it safely or pick an alternative.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Tezacaftor together?
Abametapir can raise tezacaftor levels by blocking the enzyme that clears it, so avoid using tezacaftor within 2 weeks after applying abametapir. Talk to your pharmacist or doctor to time these safely or choose another lice treatment. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Tezacaftor 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 Tezacaftor interaction managed?
What your care team may do: Try to separate the two, since abametapir's enzyme-blocking effect can last about 2 weeks after you apply it. Consider a different lice treatment if you need to stay on tezacaftor. Monitor you more closely if both are truly needed, and individualize your plan. What you should do: Keep taking your tezacaftor as prescribed. Do not stop anything on your own. Before using a… 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 Tezacaftor 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 Tezacaftor
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.
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