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A Note for Those Who Take Thyroid Hormone...

A note for those who take thyroid hormone...

We work with many folks who experience frustration because their thyroid dose never seems to be stable. 

"Every time I get my blood drawn, it seems my dose needs adjustment!"

While there are many factors that can affect the reliability of the dose, some basics that help to keep your levels stable are to:

  • Take the thyroid hormone on an empty stomach, ideally 45 minutes before eating and 2-3 hours after eating
  • Avoid taking calcium, vitamins, antacids, iron, or soy products at the same time as thyroid hormone
  • Avoid certain medications known to interfere with thyroid hormone absorption (sertraline, raloxifene, colestipol, sucralfate, fiber supplements) at the same time as the thyroid medication
  • Stick with the same brand of thyroid hormone for consistency, or for generic versions try to stick with one manufacturer
  • Stop high dose biotin supplements for 3 days before blood testing, as high dose biotin (above the RDA) can cause inaccurate thyroid blood test results

This month an interesting article was published in Frontiers in Endocrinology showing that both coffee and tea, when consumed within one hour of taking thyroid hormone, interfered with the absorption of thyroid hormone.

Shown below in the first figure is the TSH level at (1) baseline, (2) when drinking coffee or tea or both within one hour of thyroid hormone ingestion, and (3) when separating these drinks by 4 hours from the thyroid hormone. You'll notice the TSH rose substantially when they were consumed together, indicating decreased absorption of thyroid hormone.


The next figure shows the T4 levels when coffee and/or tea were taken within one hour vs. four hours apart, again showing that these drinks decreased the absorption of thyroid hormone.


Take home point

This study provides some pretty strong evidence that coffee and tea can be added to the list of substances that decrease thyroid hormone absorption.


  • If your thyroid levels are stable and you've been on the same dose for a long time, you probably don't need to overthink this and make any changes, just keep doing what is working
  • If your thyroid levels seem to fluctuate a lot, and you are often needing to change your dose, I'd recommend trying to separate cofffee and tea intake from your thyroid hormone dose by several hours if at all possible.

That's all for today. If you made it this far, thanks for reading :)

Dr. Christopher Fox I am a board-certified endocrinologist in Superior, CO, and I have been in private practice since 2003. People I work with achieve success when they learn all the ingredients of healthy lifestyle and the system to consistently follow through on good intentions. I use my knowledge of endocrine science, psychology, neuroscience, and human behavior to help people make meaningful, lasting changes in their health that they can sustain long-term.

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