Levothroid and Breastfeeding

Taking Levothroid and breastfeeding is considered a safe combination. Although studies have shown that Levothroid passes through breast milk, the medication (when used appropriately) does not cause problems in a nursing infant. In fact, many women who have an underactive thyroid may have difficultly lactating if they are not treated with medications such as Levothroid.

Levothroid and Breastfeeding: An Overview

Although Levothroid® (levothyroxine sodium) does pass through breast milk, it does not cause problems for breastfed infants when used appropriately. Even though Levothroid is usually safe for use during breastfeeding, it is still a good idea to talk with your healthcare provider about taking Levothroid if you are breastfeeding (or planning to start breastfeeding).

Levothroid and Breastfeeding: What Does the Research Say?

Studies have shown that Levothroid passes through breast milk in humans. This is not a problem, however, because Levothroid is identical to natural thyroid hormones (which also pass through breast milk). If your thyroid hormone levels are kept within a normal range, there is no reason to expect that Levothroid would cause any problems during breastfeeding. In fact, women who have an underactive thyroid (hypothyroidism) may have trouble breastfeeding unless they are treated, whether with Levothroid or other forms of thyroid replacement.
Sometimes babies are born with thyroid problems. Only small amounts of Levothroid pass through breast milk. This is not enough to treat an underactive thyroid in an infant. Instead, the infant must be treated directly.

Talking With Your Healthcare Provider About Levothroid and Breastfeeding

You should talk with your healthcare provider about Levothroid and breastfeeding. Each woman's situation is different, and you and your healthcare provider understand your situation best. After considering what you want and expect, as well as your current health situation, the two of you can make a shared decision about Levothroid and breastfeeding that is right for you. In general, Levothroid is considered safe for women who are breastfeeding and for their infants.
Last reviewed by: Kristi Monson, PharmD
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