Underactive Thyroid Diet

Medicines for an Underactive Thyroid, Diet, and Interactions

Thyroid hormone replacement therapy (levothyroxine, Levoxyl®, Synthroid®, Levothroid®, and Unithroid®) is the mainstay for treating hypothyroidism. In most cases, medicines completely control an underactive thyroid.
There are some general considerations, however, related to these medicines and diet that people should be aware of. They include:
  • Thyroid medication comes in the form of a tablet. It is usually taken once a day in the morning.
  • It is best to take these medicines on an empty stomach, 30 to 60 minutes before breakfast.
  • Try to take your thyroid medicine at the same time each day to keep an even level in your blood.
  • Thyroid hormone replacement medicines can potentially interact with many other medications and supplements, including calcium supplements, certain antacids, and certain high cholesterol medicines (see Drug Interactions With Levothyroxine). In many cases, you should separate when you take the thyroid medicine and other medicine by at least four hours.
  • Too much dietary fiber and certain other foods may decrease the absorption of thyroid medicines from the digestive tract. Try to limit the amount of these foods you eat or consume them at least four hours before or after taking your thyroid medicine. Some of these foods include:
    • Walnuts
    • Soybean oil or other soy protein products
    • Soybean flour
    • Cottonseed meal.
Last reviewed by: Arthur Schoenstadt, MD
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