Iron Supplements & Levothyroxine

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Levothyroxine is a commonly prescribed thyroid medication. Iron in tablet form is useful for those who require extra iron as a supplement to their diet. You can take both an iron supplement and levothyroxine as long as you follow dosing recommendations. A regular routine for taking your medications and supplements will maximize your body’s ability to absorb them.


Levothyroxine, sold under such brand names as Synthroid, Levoxyl and Unithroid, is chemically identical to the hormone produced naturally by the thyroid gland, which is responsible for regulating the body’s metabolism. Doctors prescribe levothyroxine to patients whose thyroids produce insufficient amounts of the hormone. Individuals who have had their thyroid gland removed surgically because of cancer or another disease also require this drug to replace the hormones their bodies can no longer produce. Levothyroxine usually must be taken every day, as long as you live.

Iron Supplements

Iron is an essential nutrient that allows your red blood cells to carry oxygen throughout the body. Iron is found in meats, fish, legumes and whole grains. Individuals who lack sufficient amounts of iron can develop iron deficiency anemia, causing them to become weak and easily fatigued. Young women of reproductive age, pregnant women and young children are most susceptible to developing anemia. Many commercial breads and cereals are fortified with iron. Ferrous sulfate is the most common dietary iron supplement, It is available as a stand-alone supplement and in multivitamins for children and adults. Other forms include ferrous fumarate, ferrous succinate and ferrous gluconate.

Recommendations for Levothyroxine Use

Because levothyroxine must be taken on an empty stomach, physicians generally recommend that patients take it first thing in the morning, and wait 30 to 60 minutes before eating or drinking anything other than water. To avoid the danger of choking or gagging, swallow a full 8-oz. glass of water with the pill. Iron can compromise the absorption of levothyroxine. For this reason, take your iron supplement either 4 hours before or after taking the drug.

Recommendations for Iron Use

The recommended dietary allowance of iron for men ages 19 and up is 8 mg daily. Women over age 51 also require 8 mg daily. During their childbearing years, however, women require an increased amount -- 18 mg daily. Pregnant women require 27 mg daily. Don't give iron supplements to an infant or child except under the direction of a physician. Too much iron can cause serious side effects.