Efavirenz and Lapatinib interaction

Efavirenz and Lapatinib: the Lapatinib prescribing label flags this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.

Major

Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.

What the FDA labels say

From the Lapatinib (TYKERB) label · effective 2026-01-27

Major

Avoid strong CYP3A4 inhibitors.

Drug interactionsby drug classView label on DailyMed

Major

If unavoidable, consider dose reduction of TYKERB in patients coadministered a strong CYP3A4 inhibitor.

Drug interactionsby drug classView label on DailyMed

Major

Avoid strong CYP3A4 inducers.

Drug interactionsby drug classView label on DailyMed

Major

If unavoidable, consider gradual dose increase of TYKERB in patients coadministered a strong CYP3A4 inducer.

Drug interactionsby drug classView label on DailyMed

Moderate

Dose adjustment of TYKERB should be considered for patients who must receive concomitant strong inhibitors or concomitant strong inducers of CYP3A4 enzymes [see Dosage and Administration (2.2)] .

Drug interactionsby drug classView label on DailyMed

Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.

Open in the checker

Not medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.