Drug interactions
Lapatinib + Voriconazole
Severity: Major
Lapatinib and Voriconazole: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Voriconazole increases lapatinib exposure, and both drugs can prolong the QT interval. This raises the risk of lapatinib toxicities such as diarrhea, hepatotoxicity, and arrhythmia.
What this interaction means in plain words
Lapatinib and Voriconazole can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Lapatinib belongs to Oncology; Voriconazole belongs to Anti Fungals.
Why it happens
Voriconazole inhibits CYP3A4, increasing lapatinib exposure, with additive QT prolongation.
What to do
Avoid the combination if possible. If it is necessary, reduce the lapatinib dose per labeling and monitor the ECG, electrolytes, and liver function.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Lapatinib and Voriconazole, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Voriconazole
- Avanafil + Voriconazole Contraindicated
- Butabarbital + Voriconazole Contraindicated
- Carbamazepine + Voriconazole Contraindicated
- Conivaptan + Voriconazole Contraindicated
- Dihydroergotamine intranasal + Voriconazole Contraindicated
- Dihydroergotamine + Voriconazole Contraindicated
Other interactions of Lapatinib
- Dofetilide + Lapatinib Contraindicated
- Ibutilide + Lapatinib Contraindicated
- Lapatinib + Pimozide Contraindicated
- Lapatinib + Saquinavir Contraindicated
- Lapatinib + Thioridazine Contraindicated
- Adagrasib + Lapatinib Major
Frequently asked questions
Can I take Lapatinib with Voriconazole?
MediHelp rates the interaction as major. Lapatinib and Voriconazole can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Voriconazole increases lapatinib exposure, and both drugs can prolong the QT interval. This raises the risk of lapatinib toxicities such as diarrhea, hepatotoxicity, and arrhythmia.
How serious is the interaction between Lapatinib and Voriconazole?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination if possible. If it is necessary, reduce the lapatinib dose per labeling and monitor the ECG, electrolytes, and liver function.
What other medicines interact with Voriconazole?
MediHelp also lists interactions of Voriconazole with, for example, Avanafil, Butabarbital, Carbamazepine. The full list is on the Voriconazole page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
