Efavirenz and Posaconazole interaction
Efavirenz and Posaconazole: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Posaconazole (NOXAFIL) label · effective 2026-02-13
Prevention or Management Efavirenz Avoid concomitant use of posaconazole with efavirenz, unless the benefit outweighs the risks.
Anti-HIV Drugs that are CYP3A4 Substrates Mechanism and Clinical Effect(s) Ritonavir and atazanavir are CYP3A4 substrates and posaconazole increased plasma concentrations of these drugs [see Clinical Pharmacology (12.3) ].
Interaction Drug Interaction Rifabutin, phenytoin, efavirenz, cimetidine, esomeprazole The drug interactions with esomeprazole and metoclopramide do not apply to Noxafil tablets or Noxafil PowderMix ( 7.3 , 12.3 ).
Effects of Noxafil and Noxafil PowderMix on Other Drugs Posaconazole is a strong CYP3A4 inhibitor.
From the Efavirenz label · effective 2024-03-31
Antifungals: Voriconazole Itraconazole Ketoconazole Posaconazole ↓ voriconazole * ↑ efavirenz * ↓ itraconazole * ↓ hydroxyitraconazole * ↓ ketoconazole ↓ posaconazole * Efavirenz and voriconazole should not be coadministered at standard doses.
QT Prolonging Drugs There is limited information available on the potential for a pharmacodynamic interaction between efavirenz and drugs that prolong the QTc interval.
Consider alternative antifungal treatment because no dose recommendation for itraconazole can be made.
Consider alternative antifungal treatment because no dose recommendation for ketoconazole can be made.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot 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.