Optimizing Your Thyroid Treatment: Why Other Medications Matter

By Jeffrey R. Garber, FACP, FACE

In 2013, the American College of Endocrinology (ACE) – the scientific, educational and charitable arm of the American Association of Clinical Endocrinologists (AACE) – introduced the Same/Same/Same awareness campaign (http://www. thyroidawareness.com/my-pillcheck) to help those on thyroid medication consistently maintain normal thyroid hormone levels. Taking the same dosage of the same medication (whether brand name or generic) at the same time of day, separate from food and supplements (see below) is critical to achieving this goal.

Another important factor to be aware of is that supplements and medications may affect thyroid hormone levels in several ways. They can interfere with how your body absorbs thyroid hormone and change the speed that your body uses it (metabolism). In some cases, medication may damage the thyroid gland or the pituitary gland, which sits at the base of the brain and regulates how your thyroid works. Therefore, it is very important to tell the medical professional who is prescribing and monitoring your thyroid hormone levels what supplements and medications you are taking. Below is a list of medicines, supplements and foods that can hinder the effectiveness of thyroid medicines.

Drugs and foods that may affect your thyroid hormone levels

Adapted from “Thyroid Disease-Understanding hypothyroidism and hyperthyroidism, a Harvard Medical School Special Report,” Copyright ©2015 by Harvard University.

Cancer Therapies

  • Asparaginase
  • Bexatorene*
  • Fluorouacil
  • Interferon*
  • Interleukin
  • Ipilimumab*
  • Nivolumab*
  • Pembrolizumab*
  • Tamoxifen
  • Thalidomide and Lenalidomide
  • Tyrosine kinase inhibitors (Sunitinib, Sorafenib)*

Cardiovascular therapies

  • Amiodarone*
  • Furosemide
  • Heparin
  • Oral anticoagulants

Cholesterol therapies

  • Bile acid sequestrants, including Cholestyramine*, Clofibrate and Colestipol*
  • Slow-release Niacin

Gastrointestinal Therapies

  • Aluminum hydroxide antacids
  • Cation-exchange resins
  • Charcoal
  • Proton-pump inhibitors
  • Sucralfate

Hormonal Therapies

  • Androgens/anabolic steroids
  • Dopaminergic drugs, including Bromocriptine and Cabergoline
  • Estrogens
  • Glucocorticoids such as Prednisone
  • Growth hormone
  • Metoclopramide
  • Raloxifene

Neurologic/Psychiatric Therapies

  • Anticonvulsants, including Phenytoin*, Phenobarbital*, and Carbamazepine*
  • Lithium*
  • Sertraline*
  • Other antidepressants and antipsychotic agents, including Clomipramine and Quetiapine

Nutritional Supplements

  • Calcium carbonate
  • Ferrous sulfate (iron)
  • Iodine* (including kelp supplements)
  • Glucocorticoids such as Prednisone
  • Multivitamins (presumably because of iron and calcium content)


  • Espresso coffee
  • Grapefruit
  • High-fiber diet
  • Soy

Other Medicines

  • Antituberculosis drugs (Rifampicin, Ethionamide)
  • Bisphosphonates taken orally, such as Alendronate
  • Ciprofloxacin
  • Methadone
  • Nonsteroidal anti-inflammatory drugs such as Meclofenamic Acid, Mefenamic Acid, Phenylbutazone
  • Orlistat
  • Orphenadrine
  • Propranolol
  • Radiographic agents (such as contrast agents containing Iodine)*
  • Salicylates (high doses of Aspirin and Salsalate)
  • Sulfonamides (Acetazolamide, Sulfisoxazole)
  • Sulfonylureas

(*These drugs can have a major impact on thyroid treatment.)