What foods and supplements can interact with thyroid medication?

Several minerals in your diet can change the amount of thyroid replacement medication that gets absorbed into the bloodstream.

In particular, iron from food or iron pills, and calcium from food or calcium supplements can keep your full dose of thyroid medicine from being absorbed.

Instead of changing your diet, the best way to keep your thyroid treatment stable is to take your thyroid pill at a time separate from your mealtime. Take your daily pill one hour before eating or at least two hours after eating. This will ensure you get your full dose.

Anti-acid medicines can also change the amount of thyroid medicine that gets absorbed. If you use a daily anti-acid treatment, your doctor may want to do a blood test to make sure your thyroid dose is still right for you.

There are numerous foods and medications that interact with levothyroxine. These foods and medications do not need to be avoided completely, but should not be ingested within 4 hours of taking levothyroxine. Some of these foods and medications include iron, calcium, multivitamins, soy, phenytoin, some estrogen products, and some cholesterol-lowering medications. These substances can alter the absorption of thyroid hormone. If you are taking these medications, please talk to your physician or pharmacists about possible interactions.