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How to take Your Thyroid Drugs

Frequently Asked Questions about Food, Drug and Supplement Interactions


Updated May 30, 2014

Young woman taking pill, portrait, close-up
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Many people ask about specific drugs, supplements and foods and whether or not you can take them when you're taking thyroid hormones. Here's a review of some of the current thinking. (Please note that this is by no means a comprehensive listing of all drug interactions, so be sure to ask for and read your patient insert that comes with your prescriptions, and always talk to your doctor and pharmacist regarding specific questions.)

Q. Should You Take Your Thyroid Hormone With Food vs. An Empty Stomach?

Food may delay or reduce the absorption of many drugs, including thyroid hormone. Food can often slow the process of the stomach entering, but it may also affect absorption of the drug you're taking by binding with it, by decreasing access to absorption sites, by altering the rate at which it dissolves, or by changing the stomach's pH balance. This is why many doctors recommend that for best absorption of your thyroid hormone, you should take it first thing the morning, on an empty stomach, one hour before eating.

Many doctors recommend that for best absorption of your thyroid hormone, take it first thing the morning, on an empty stomach, and wait one hour before eating, and at least two hours before taking any vitamin with iron.

However, if you cannot take it this way, consistency becomes the key. If you're going to take your thyroid hormone with food, take it every day with food, consistently. If you've changed from taking it on an empty stomach, then around six to eight weeks after you start taking it with food, you should have another TSH test to ensure you're receiving the proper amount of thyroid hormone. Taking the drug with food might inhibit absorption somewhat, but this safety check will make sure your dosage gets tweaked if it needs to be changed slightly. But again, CONSISTENCY. Don't take it some days with food, some days without, or you're sure to have erratic absorption, and it will be harder to regulate your TSH levels.

Q. What is the Impact of a High Fiber Diet?

Given that many people on thyroid replacement therapy are fighting an additional battle to lose weight, high fiber diets are also an issue. Anything that affects your digestion speed or speed of absorption of items into the stomach can have an effect on your absorption of thyroid hormone. Since high-fiber diets can, ahem, speed things up a bit, they are known to inhibit absorption for some people. So, should you forget about eating high-fiber? Absolutely not!!! Since the benefits of fruits, vegetables and a high-fiber diet are known, again, the issue here is consistency. If you are already eating a high-fiber diet regularly, and have regular TSH testing done, your dosage level is appropriate for you, given your diet. If you are starting a new regimen of eating high-fiber, plan to get tested around six to eight weeks after you change your diet, to make sure you're receiving the proper amount of thyroid hormone. But be consistent. Don't jump around, or you'll have erratic absorption, and that can wreak havoc on TSH levels...AND how you feel! But again, taking your thyroid hormone first thing a.m. on an empty stomach, and waiting at least an hour to eat, will ensure maximum absorption, whatever your diet is!

Q. What About Iodine and Kelp Supplements?

While some herbalists and vitamin proponents recommend iodine tablets or kelp supplements (which are high in iodine) for people with thyroid problems, you need to be extremely careful about any decision to take iodine or kelp supplements if you are on thyroid hormone replacement therapy.

The thinking behind taking iodine or kelp is that in many parts of the world, goiters and thyroid disease are related to iodine deficiency. In the U.S. and other developed countries, iodine deficiency is not very common anymore, due to the addition of iodine to salt -- iodized salt -- and other food products. In fact, the most common forms of thyroid disease found in the U.S. -- autoimmune thyroid diseases like Graves' Disease or Hashimoto's Thyroiditis -- have nothing to do with iodine deficiency at all. Actually, thyroids are extremely sensitive to iodine, and you need to be careful about adding too much iodine to the diet as it can irritate or aggravate the thyroid. Most doctors say not to worry about some iodized salt, or the iodine present in a food item such as an occasional sushi dinner. But even alternative nutritional doctor Stephen Langer, author of Solved: The Riddle of Illness, the follow-up book to Broda Barnes' Hypothyroidism: The Unsuspected Illness, advises against taking iodine or kelp supplements for people with autoimmune thyroid disease.

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