Misc Antifungal Agents/Astemizole; Terfenadine 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:

Very Serious. 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:

When these two medicines are taken together, your body may not process your allergy medicine properly.

What might happen:

Your blood levels of your allergy medicine may increase and cause life-threatening effects on your heart.

What you should do about this interaction:

Contact your healthcare professionals (e.g. doctor or pharmacist) as soon as possible about taking these two medicines together. They may already be aware of this interaction and may be monitoring you for it. You may need to change to an different allergy medicine, or stop taking it while taking the antifungal medicine. Do not start, stop, or change the dosage of any medicine before checking with them first.

View Reference
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  • 2.Eller MG, Okerholm RA. Pharmacokinetic interaction between terfenadine and ketoconazole. Clin Pharmacol Ther 1991 Feb;49:130.
  • 3.Mathews DR, McNutt B, Okerholm R, Flicker M, McBride G. Torsades de pointes occurring in association with terfenadine use. JAMA 1991 Nov 6; 266(17):2375-6.
  • 4.Data on file. Janssen Pharmaceutica Products, L.P. July 31, 1992.
  • 5.Pohjola-Sintonen S, Viitasalo M, Toivonene L, Neuvonen P. Torsades de pointes after terfenadine-itraconazole interaction. BMJ 1993 Jan 16; 306(6871):186.
  • 6.Honig PK, Wortham DC, Zamani K, Conner DP, Mullin JC, Cantilena LR. Terfenadine-ketoconazole interaction. Pharmacokinetic and electrocardiographic consequences. JAMA 1993 Mar 24-31;269(12):1513-8.
  • 7.Woosley RL, Chen Y, Freiman JP, Gillis RA. Mechanism of the cardiotoxic actions of terfenadine. JAMA 1993 Mar 24-31;269(12):1532-6.
  • 8.Peck CC, Temple R, Collins JM. Understanding consequences of concurrent therapies. JAMA 1993 Mar 24-31;269(12):1550-2.
  • 9.Claritin (loratadine) US prescribing information. Schering-Plough Corporation January, 1997.
  • 10.Zimmermann M, Duruz H, Guinand O, Broccard O, Levy P, Lacatis D, Bloch A. Torsades de Pointes after treatment with terfenadine and ketoconazole. Eur Heart J 1992 Jul;13(7):1002-3.
  • 11.Affrime MB, Lorber R, Danzig M, Cuss F, Brannan MD. Three month evaluation of electrocardiographic effects of loratatdine in humans. J Allergy Clin Immunol 1993;91(1):259.
  • 12.Crane JK, Shih HT. Syncope and cardiac arrhythmia due to an interaction between itraconazole and terfenadine. Am J Med 1993 Oct;95(4):445-6.
  • 13.Diflucan (fluconazole) US prescribing information. Pfizer Inc. January, 2023.
  • 14.Seldane (terfenadine) US prescribing information. Hoechst-Marion Roussel September, 1997.
  • 15.Sporanox (itraconazole) US prescribing information. Janssen Pharmaceutica Products, L.P. March, 1994.
  • 16.Hismanal (astemizole) US prescribing information. Janssen Pharmaceutica Products, L.P. February, 1998.
  • 17.Allegra (fexofenadine hydrochloride) US prescribing information. Sanofi-Aventis U.S. LLC October, 2006.
  • 18.Mizollen (mizolastine) US prescribing information. Lorex Synthelab September 29, 1997.
  • 19.Vfend (voriconazole) US prescribing information. Pfizer Inc. October, 2022.
  • 20.Noxafil (posaconazole) UK summary of product characteristics. Schering-Plough Ltd. January, 2022.
  • 21.Noxafil (posaconazole) US prescribing information. Schering Corporation March, 2019.
  • 22.Drew BJ, Ackerman MJ, Funk M, Gibler WB, Kligfield P, Menon V, Philippides GJ, Roden DM, Zareba W. Prevention of torsade de pointes in hospital settings: a scientific statement from the American Heart Association and the American College of Cardiology Foundation. J Am Coll Cardiol 2010 Mar 2;55(9):934-47.
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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.