Itraconazole; Ketoconazole; Posaconazole/Efavirenz Interactions

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

Efavirenz may speed up how quickly your liver processes your antifungal medicine.

What might happen:

Your antifungal may not work as well.

What you should do about this interaction:

Make sure your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together. Your doctor may want to change your medicine.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.

  • 1.Sustiva (efavirenz) US prescribing information. Bristol-Myers Squibb Company October, 2019.
  • 2.Sustiva (efavirenz) Canadian prescribing information. Bristol-Myers Squibb January 8, 2007.
  • 3.Sustiva (efavirenz) UK summary of product characteristics. Bristol-Myers Squibb Pharmaceuticals Ltd January 26, 2007.
  • 4.Atripla (efavirenz/emtricitabine/tenofovir disoproxil fumarate) US prescribing information. Gilead Sciences, Inc. October, 2019.
  • 5.Sriwiriyajan S, Mahatthanatrakul W, Ridtitid W, Jaruratanasirikul S. Effect of efavirenz on the pharmacokinetics of ketoconazole in HIV-infected patients. Eur J Clin Pharmacol 2007 May;63(5):479-83.
  • 6.Noxafil (posaconazole) US prescribing information. Merck & Co. Inc September, 2016.
  • 7.Sporanox (itraconazole) US prescribing information. Janssen Pharmaceutica Products, L.P. May, 2018.

Selected from data included with permission and copyrighted by First Databank, Inc. This copyrighted material has been downloaded from a licensed data provider and is not for distribution, except as may be authorized by the applicable terms of use.

CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.