Iron and Thyroid Medications

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In addition to taking medication on a daily basis, those with thyroid dysfunction must also watch out for possible drug interactions that can cause thyroid medication to not work properly. Since iron supplements may pose potential problems for those with thyroid dysfunction, it's best to talk with your doctor to determine the best way for you to get your iron.

About Thyroid Medications

People whose thyroid glands don't work properly must take thyroid medication to ensure proper levels of thyroid-stimulating hormone in the blood. Medications used to treat overactive thyroid include ethimazole and propylthioracil, while levothyroxine sodium is used to treat underactive thyroid function. These medications require precise dosing to keep thyroid hormone levels stable and normal, and patients generally need periodic blood tests to monitor the effectiveness of treatment. Because certain medications, vitamins and supplements may interfere with thyroid medication, it's important to check with your doctor before taking new medicines or supplements.

Iron Interference

According to the University of Maryland Medical Center, iron supplements can interfere with the absorption of thyroid medication and decrease the effectiveness of the medicine. Before taking an iron supplement or any type of multivitamin that contains iron, check with your doctor. If you need to take an iron supplement, your doctor may advise you to take it a few hours before or after you take your thyroid medication. You may also need closer monitoring of your thyroid hormone levels to make sure your medication continues to work properly.


If you're concerned about taking an iron supplement that may interfere with your thyroid medication, you can always get the iron your body needs the old-fashioned way -- through the foods you eat. While iron supplements can cause trouble for those with thyroid dysfunction, getting iron through food won't interfere with your medication. To avoid potential problems with supplements, make iron-rich foods such as meat, liver, spinach and lentils a part of your regular diet.

Increasing Iron Absorption

If you choose not to take iron supplements, try eating iron-rich foods along with foods containing vitamin C, such as citrus fruits or juices, red bell peppers or brussels sprouts. The Centers for Disease Control and Prevention notes that vitamin C helps your body absorb iron better, especially when taken at the same time.