Selected Antihistamines/Selected MAOIs 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:

Monoamine oxidase inhibitors (MAOIs) may increase the effects of your antihistamine.

What might happen:

Your blood pressure may drop dangerously low.

What you should do about this interaction:

Let your healthcare professionals (e.g. doctor or pharmacist) know right away that you are taking these medicines together. Your doctor may want to change your medicine. Let your doctor know right away if you have any weakness, dizziness, fainting, or blurred vision.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.Zadine (azatadine maleate) Australian prescribing information. Schering-Plough Corporation January, 1992.
  • 2.Ambi 1000/5 (guaifenesin/carbetapentane) US prescribing information. AMBI Pharmaceuticals, Inc. March, 2006.
  • 3.PediaTan (chlorpheniramine tannate) US prescribing information. ProEthic Pharmaceuticals, Inc. June, 2006.
  • 4.Carbinoxamine maleate US prescribing information. Zeris Pharma, L.L.C. February, 2007.
  • 5.Cyproheptadine hydrochloride US prescribing information. Cypress Pharmaceutical, Inc. November, 2006.
  • 6.Bonjesta (doxylamine and pyridoxine) US prescribing information. Duchesnay, Inc. June, 2018.
  • 7.Kahn DA. Possible toxic interaction between cyproheptadine and phenelzine. Am J Psychiatry 1987 Sep;144(9):1242-3.
  • 8.Ramsay RR, Dunford C, Gillman PK. Methylene blue and serotonin toxicity: inhibition of monoamine oxidase A (MAO A) confirms a theoretical prediction. Br J Pharmacol 2007 Nov;152(6):946-51.
  • 9.Peter C, Hongwan D, Kupfer A, Lauterburg BH. Pharmacokinetics and organ distribution of intravenous and oral methylene blue. Eur J Clin Pharmacol 2000 Jun;56(3):247-50.

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.