Itraconazole; Ketoconazole/Isoniazid 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:

Severe. These medicines may interact and cause very harmful effects and are usually not taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

Isoniazid speeds up how quickly your liver processes itraconazole and ketoconazole.

What might happen:

The amount of itraconazole or ketoconazole in your blood may be decreased and they might not work as well against your infection.

What you should do about this interaction:

Make sure that your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together. Your doctor may want to consider changing one or both of the medicines that you are taking.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.Sporanox (itraconazole) US prescribing information. Janssen Pharmaceutica Products, L.P. May, 2018.
  • 2.Nizoral (ketoconazole oral) US prescribing information. Janssen Pharmaceuticals February, 2014.
  • 3.Engelhard D, Stutman HR, Marks MI. Interaction of ketoconazole with rifampin and isoniazid. N Engl J Med 1984 Dec 27;311(26):1681-3.
  • 4.Pilheu JA, Galati MR, Yunis AS, De Salvo MC, Negroni R, Garcia Fernandez JC, Mingolla L, Rubio MC, Masana M, Acevedo C. Pharmacokinetic interaction of ketoconazole, isoniazid and rifampicin. Medicina (B Aires) 1989; 49(1):43-7.

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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.