Do Allergy Drugs Interact with Synthroid?

  • Medical Author:
    Ruchi Mathur, MD, FRCP(C)

    Ruchi Mathur, MD, FRCP(C) is an Attending Physician with the Division of Endocrinology, Diabetes and Metabolism and Associate Director of Clinical Research, Recruitment and Phenotyping with the Center for Androgen Related Disorders, Department of Obstetrics and Gynecology at Cedars-Sinai Medical Center.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Ask the experts

I am currently taking Synthroid and have been prescribed cetirizine (Zyrtec) and mometasone furoate (Nasonex), do these medications effect Synthroid?

Doctor's response

Zyrtec and Nasonex do not interact with Synthroid directly. Although there is a very slight chance that Nasonex can increase the effect of Synthroid, this is exceedingly rare. Regardless, Synthroid should be taken on an empty stomach for the best absorption. If you are over-replaced on Synthroid and are running "hyper" (meaning that you have symptoms of hyperthyroidism from taking too much medication) there is a possibility that these medications may exacerbate your symptoms.

Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care


FDA Prescribing Information for Synthroid

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Reviewed on 7/18/2017